Criminalization of breach of trust is unique to Korea and has served as an ultima ratio for the protection of property rights. Unfortunately, the Korean Supreme Court's rulings on breach of trust have been the subject of scholarly debate for various reasons, including them being against nullum crimen sine lege. In that regard, the recent Supreme Court decision on whether “not returning the mistakenly transferred virtual assets” constitutes breach of trust presents an opportunity to review the features of breach of trust in conjunction with virtual assets (VAs). The acquittal may reflect the recent shift of the Supreme Court towards narrowing the scope of breach of trust. Though not wholly consistent with the precedents, it does reflect the trend to strengthen the principle of nullum crimen sine lege. However, in light of the rising popularity of VAs in Korean society and continuous adoption of regulations on VAs at domestic and international levels, including the travel rule, there may be a room for reconsideration in future.