Yohei Oogawa knew much more than Takashi Hasegawa; he was aware that the murderer had connections with the high-tech Drone that had caused a commotion in Japan and also knew about the display of power by the Drone on that night. This led him to deduce that the Drone contained advanced technology. Although he believed in Hideo Oogawa's strength, he wasn't sure if Hideo would return safely. Hence, he thought that the murderer had not died but had killed Hideo Oogawa and escaped.
Driven by enormous greed, Yohei Oogawa began to investigate the old grudges his family had formed in China, hoping to find the murderer's trail through this information. Then, by tracing the connection, he aimed to locate the factory or laboratory that produced the Drone and acquire the advanced technology it possessed. Once he obtained this high-tech technology, the revival of the Oogawa Family was within reach, and all the previous losses would have been worth it.
