Digital Legacy Inheritance System Architecture: 
A Systematic Analysis Using PlantUML C4 Model

Osamu Okumura

doi:doi:10.11648/j.ae.20250902.13

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Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model

Osamu Okumura^*

Published in Applied Engineering (Volume 9, Issue 2)

Received: 3 November 2025 Accepted: 20 November 2025 Published: 17 December 2025

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Abstract

This paper systematically analyzes the pressing issue of "digital legacy inheritance" in modern society using the C4 model (Context, Container, Component, Code) software architecture design methodology, proposing an integrated solution framework across three layers: technology, legal systems, and ethics. While traditional inheritance law assumes analog assets, this research visualizes problems unique to digital assets—"loss of access rights," "contract continuity," and "conflicts with personality rights"—and presents implementable inheritance system architecture. The C4 model's progressive refinement approach enables problem space structuring, stakeholder communication facilitation, and bridging to implementation. This paper progressively presents diagrams using the example of the digital legacy inheritance system "LCI (Legacy Continuity Initiative)" across four layers, revealing the complex interplay between technical, legal, social, and ethical dimensions. The four-layer progressive refinement demonstrates architectural clarity through hybrid authentication bridging analog legal validity and digital security, ethical integration with AI serving as an ethical gatekeeper representing the deceased's will, and practical implementability providing a concrete roadmap from abstract problem to deployable solution. Key contributions include the first systematic C4 model application to digital legacy inheritance, hybrid authentication architecture combining physical seal recognition with cryptographic verification, AI ethical gatekeeper concept for enforcing deceased's pre-mortem wishes, quantitative evidence showing the LCI approach reduces asset dormancy from 78% to 5%, and an international comparative framework analyzing Germany, France, USA, and Japan. As of 2025, approximately 60 million people die annually worldwide, with an estimated 80%+ possessing some form of digital assets, yet most are not properly inherited and become "digital dark matter." The LCI framework offers a comprehensive architectural approach requiring coordinated action across technical, legal, and social domains to address this present crisis.

Published in	Applied Engineering (Volume 9, Issue 2)
DOI	10.11648/j.ae.20250902.13
Page(s)	88-108
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Digital Legacy, C4 Model, Legacy Continuity, Digital End-of-Life Planning, Access Rights Inheritance, AI Ethics, Analog Authentication, Cloud Asset Management

References

[1]	Edwards, L., & Harbinja, E. (2013). "Protecting post-mortem privacy: Reconsidering the privacy interests of the deceased in a digital world." Cardozo Arts & Entertainment Law Journal, 32(1), 83-143.
[2]	Maciel, C., & Pereira, V. C. (2013). Digital legacy and interaction: Post-mortem issues. Springer International Publishing.
[3]	Brown, S. (2018). The C4 model for visualising software architecture. https://c4model.com
[4]	Ministry of Internal Affairs and Communications (2024). White Paper on Information and Communications in Japan, pp. 234-256.
[5]	Harbinja, E. (2017). "Does the EU General Data Protection Regulation provide adequate protection of digital assets on death?" Legal Studies, 37(1), 19-42.
[6]	German Federal Court of Justice (2018). BGH, Urteil vom 12.07.2018 - III ZR 183/17 (Facebook inheritance case).
[7]	Uniform Law Commission (2015). Revised Uniform Fiduciary Access to Digital Assets Act.

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APA Style

Okumura, O. (2025). Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Applied Engineering, 9(2), 88-108. https://doi.org/10.11648/j.ae.20250902.13

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Okumura, O. Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Appl. Eng. 2025, 9(2), 88-108. doi: 10.11648/j.ae.20250902.13

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AMA Style

Okumura O. Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Appl Eng. 2025;9(2):88-108. doi: 10.11648/j.ae.20250902.13

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@article{10.11648/j.ae.20250902.13,
  author = {Osamu Okumura},
  title = {Digital Legacy Inheritance System Architecture: 
A Systematic Analysis Using PlantUML C4 Model},
  journal = {Applied Engineering},
  volume = {9},
  number = {2},
  pages = {88-108},
  doi = {10.11648/j.ae.20250902.13},
  url = {https://doi.org/10.11648/j.ae.20250902.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ae.20250902.13},
  abstract = {This paper systematically analyzes the pressing issue of "digital legacy inheritance" in modern society using the C4 model (Context, Container, Component, Code) software architecture design methodology, proposing an integrated solution framework across three layers: technology, legal systems, and ethics. While traditional inheritance law assumes analog assets, this research visualizes problems unique to digital assets—"loss of access rights," "contract continuity," and "conflicts with personality rights"—and presents implementable inheritance system architecture. The C4 model's progressive refinement approach enables problem space structuring, stakeholder communication facilitation, and bridging to implementation. This paper progressively presents diagrams using the example of the digital legacy inheritance system "LCI (Legacy Continuity Initiative)" across four layers, revealing the complex interplay between technical, legal, social, and ethical dimensions. The four-layer progressive refinement demonstrates architectural clarity through hybrid authentication bridging analog legal validity and digital security, ethical integration with AI serving as an ethical gatekeeper representing the deceased's will, and practical implementability providing a concrete roadmap from abstract problem to deployable solution. Key contributions include the first systematic C4 model application to digital legacy inheritance, hybrid authentication architecture combining physical seal recognition with cryptographic verification, AI ethical gatekeeper concept for enforcing deceased's pre-mortem wishes, quantitative evidence showing the LCI approach reduces asset dormancy from 78% to 5%, and an international comparative framework analyzing Germany, France, USA, and Japan. As of 2025, approximately 60 million people die annually worldwide, with an estimated 80%+ possessing some form of digital assets, yet most are not properly inherited and become "digital dark matter." The LCI framework offers a comprehensive architectural approach requiring coordinated action across technical, legal, and social domains to address this present crisis.},
 year = {2025}
}

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TY  - JOUR
T1  - Digital Legacy Inheritance System Architecture: 
A Systematic Analysis Using PlantUML C4 Model
AU  - Osamu Okumura
Y1  - 2025/12/17
PY  - 2025
N1  - https://doi.org/10.11648/j.ae.20250902.13
DO  - 10.11648/j.ae.20250902.13
T2  - Applied Engineering
JF  - Applied Engineering
JO  - Applied Engineering
SP  - 88
EP  - 108
PB  - Science Publishing Group
SN  - 2994-7456
UR  - https://doi.org/10.11648/j.ae.20250902.13
AB  - This paper systematically analyzes the pressing issue of "digital legacy inheritance" in modern society using the C4 model (Context, Container, Component, Code) software architecture design methodology, proposing an integrated solution framework across three layers: technology, legal systems, and ethics. While traditional inheritance law assumes analog assets, this research visualizes problems unique to digital assets—"loss of access rights," "contract continuity," and "conflicts with personality rights"—and presents implementable inheritance system architecture. The C4 model's progressive refinement approach enables problem space structuring, stakeholder communication facilitation, and bridging to implementation. This paper progressively presents diagrams using the example of the digital legacy inheritance system "LCI (Legacy Continuity Initiative)" across four layers, revealing the complex interplay between technical, legal, social, and ethical dimensions. The four-layer progressive refinement demonstrates architectural clarity through hybrid authentication bridging analog legal validity and digital security, ethical integration with AI serving as an ethical gatekeeper representing the deceased's will, and practical implementability providing a concrete roadmap from abstract problem to deployable solution. Key contributions include the first systematic C4 model application to digital legacy inheritance, hybrid authentication architecture combining physical seal recognition with cryptographic verification, AI ethical gatekeeper concept for enforcing deceased's pre-mortem wishes, quantitative evidence showing the LCI approach reduces asset dormancy from 78% to 5%, and an international comparative framework analyzing Germany, France, USA, and Japan. As of 2025, approximately 60 million people die annually worldwide, with an estimated 80%+ possessing some form of digital assets, yet most are not properly inherited and become "digital dark matter." The LCI framework offers a comprehensive architectural approach requiring coordinated action across technical, legal, and social domains to address this present crisis.
VL  - 9
IS  - 2
ER  -

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Author Information

Osamu Okumura

Independent Researcher, Tokyo, Japan

Contact Email

http://orcid.org/0009-0006-0015-938X

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APA Style

Okumura, O. (2025). Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Applied Engineering, 9(2), 88-108. https://doi.org/10.11648/j.ae.20250902.13

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ACS Style

Okumura, O. Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Appl. Eng. 2025, 9(2), 88-108. doi: 10.11648/j.ae.20250902.13

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AMA Style

Okumura O. Digital Legacy Inheritance System Architecture: A Systematic Analysis Using PlantUML C4 Model. Appl Eng. 2025;9(2):88-108. doi: 10.11648/j.ae.20250902.13

Copy | Download

@article{10.11648/j.ae.20250902.13,
  author = {Osamu Okumura},
  title = {Digital Legacy Inheritance System Architecture: 
A Systematic Analysis Using PlantUML C4 Model},
  journal = {Applied Engineering},
  volume = {9},
  number = {2},
  pages = {88-108},
  doi = {10.11648/j.ae.20250902.13},
  url = {https://doi.org/10.11648/j.ae.20250902.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ae.20250902.13},
  abstract = {This paper systematically analyzes the pressing issue of "digital legacy inheritance" in modern society using the C4 model (Context, Container, Component, Code) software architecture design methodology, proposing an integrated solution framework across three layers: technology, legal systems, and ethics. While traditional inheritance law assumes analog assets, this research visualizes problems unique to digital assets—"loss of access rights," "contract continuity," and "conflicts with personality rights"—and presents implementable inheritance system architecture. The C4 model's progressive refinement approach enables problem space structuring, stakeholder communication facilitation, and bridging to implementation. This paper progressively presents diagrams using the example of the digital legacy inheritance system "LCI (Legacy Continuity Initiative)" across four layers, revealing the complex interplay between technical, legal, social, and ethical dimensions. The four-layer progressive refinement demonstrates architectural clarity through hybrid authentication bridging analog legal validity and digital security, ethical integration with AI serving as an ethical gatekeeper representing the deceased's will, and practical implementability providing a concrete roadmap from abstract problem to deployable solution. Key contributions include the first systematic C4 model application to digital legacy inheritance, hybrid authentication architecture combining physical seal recognition with cryptographic verification, AI ethical gatekeeper concept for enforcing deceased's pre-mortem wishes, quantitative evidence showing the LCI approach reduces asset dormancy from 78% to 5%, and an international comparative framework analyzing Germany, France, USA, and Japan. As of 2025, approximately 60 million people die annually worldwide, with an estimated 80%+ possessing some form of digital assets, yet most are not properly inherited and become "digital dark matter." The LCI framework offers a comprehensive architectural approach requiring coordinated action across technical, legal, and social domains to address this present crisis.},
 year = {2025}
}

Copy | Download

TY  - JOUR
T1  - Digital Legacy Inheritance System Architecture: 
A Systematic Analysis Using PlantUML C4 Model
AU  - Osamu Okumura
Y1  - 2025/12/17
PY  - 2025
N1  - https://doi.org/10.11648/j.ae.20250902.13
DO  - 10.11648/j.ae.20250902.13
T2  - Applied Engineering
JF  - Applied Engineering
JO  - Applied Engineering
SP  - 88
EP  - 108
PB  - Science Publishing Group
SN  - 2994-7456
UR  - https://doi.org/10.11648/j.ae.20250902.13
AB  - This paper systematically analyzes the pressing issue of "digital legacy inheritance" in modern society using the C4 model (Context, Container, Component, Code) software architecture design methodology, proposing an integrated solution framework across three layers: technology, legal systems, and ethics. While traditional inheritance law assumes analog assets, this research visualizes problems unique to digital assets—"loss of access rights," "contract continuity," and "conflicts with personality rights"—and presents implementable inheritance system architecture. The C4 model's progressive refinement approach enables problem space structuring, stakeholder communication facilitation, and bridging to implementation. This paper progressively presents diagrams using the example of the digital legacy inheritance system "LCI (Legacy Continuity Initiative)" across four layers, revealing the complex interplay between technical, legal, social, and ethical dimensions. The four-layer progressive refinement demonstrates architectural clarity through hybrid authentication bridging analog legal validity and digital security, ethical integration with AI serving as an ethical gatekeeper representing the deceased's will, and practical implementability providing a concrete roadmap from abstract problem to deployable solution. Key contributions include the first systematic C4 model application to digital legacy inheritance, hybrid authentication architecture combining physical seal recognition with cryptographic verification, AI ethical gatekeeper concept for enforcing deceased's pre-mortem wishes, quantitative evidence showing the LCI approach reduces asset dormancy from 78% to 5%, and an international comparative framework analyzing Germany, France, USA, and Japan. As of 2025, approximately 60 million people die annually worldwide, with an estimated 80%+ possessing some form of digital assets, yet most are not properly inherited and become "digital dark matter." The LCI framework offers a comprehensive architectural approach requiring coordinated action across technical, legal, and social domains to address this present crisis.
VL  - 9
IS  - 2
ER  -

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