There is a striking contrast in how to evaluate An Jung-geun in the international circle. Each country has a different view, based on their own national interests. In this situation, it is necessary to shed a new light on this issue beyond national interests. An Jung-geun was an nationalist activist that led the independence and liberation efforts of our people and a military person who fulfilled the true military spirit as well. He was also an educator with a solid Catholic faith and is recognized as a practical theologist that was ahead of his time. An Jung-geun’s image as a patriot that stood for nationalism is so dominant that his life as a devout Catholic layman has not received the deserved attention. His assassination of Ito Hirobumi is also widely evaluated as an expression of patriotism, but there is a greater causal side to his actions with wider implications. The assassination of Ito Hirobumi by An Joong-geun falls into the scope of an action of self-defense killing that is acceptable by the Catholic Church. This incident may look like an act of personal motivation on the surface, but An Joong-geun accurately recognized the difference between his actions as a soldier and the actions that he took to abide by the laws of the Catholic church. Exactly being aware of these differences, he continued to argue and plea to highlight these differences during the process of his trial. The trial of An Joong-geun has been proven to have been a blatantly illegal trial and invalid in view of international law based on precedent researches, and a re-trial at the International Court of Justice (ICJ) is currently being prepared by various organizations and law officials of Korea. The assassination of Ito Hirobumi by An Joong-geun was verified to have legitimacy in view of both international law and the positive law of the Catholic Church. Despite this fact, the Japanese government continues to claim to this day that An Joong-geun is a terrorist and that he was a killer sentenced to death penalty through a just trial process. This situation is not only counterproductive for improving the relationship between Korean and Japan but is both a distortion of history and also a case of blatant defamation of the deceased. The Japanese government persists to this day that there were no problems with the trial and sentencing and An Joong-geun was merely a terrorist. If this kind of defamation An Joong-geun continues defamation, the Theory of Oriental Peace that An Joong-geun advocated won't be realized in the near future. The assassination by An Joong-geun was done, as his claimed, for the peace of East Asia, in turn for the peace of the world. For Korea and Japan to overcome the historical tensions from the An Joonggeun incident, the legal issues raised by Japan must first be resolved. This article aims to illuminate that the assassination by An Joong-geun was a legitimate self-defense action when both viewed by international law and viewed by the law of the Catholic Church. It is of particular note that from the viewpoint of the Catholic Church the action of An Joong-geun transcends an act of self-defense and deserves the highest admiration. Continued irrational disputes and tensions among nations becomes a cause that undermines peaceful coexistence and can possibly trigger a war. If Korean and Japan can resolve the incident of An Joong-geun legally, then the possibility of ultimate reconciliation between the two countries increases and a bright future is expected to come. An Joong-geun was aware that his actions were for the sake of common good and consistently asserted that his assassination of Ito Hirobumi was not against the law. To prevent the continuous defamation of An Joonggeun by the Japanese government and pro-Japanese groups and to improve Korea-Japan relations, the wounds between the two nations must be healed and reconciled. This process of healing and reconciliation must reach beyond the scope of nationalism, which will be possible only when the incident is viewed from an objective legal perspective beyond nationalism. Only when both Korea and Japan agree to accept a justifiable common ground in the legal evaluation of the An Joong-geun incident can they begin to construct a solid ground for their productive future together based on true reconciliation.