As a child, Yaemon desired to be the next head of the Ikeda Clan. He tried to prove himself worthy of the title by killing several prisoners, claiming that he had used Kimoarai on them. Upon seeing this, his father tried to punish him, but was stopped by Asaemon. This incident had led to the title "17th Ikeda Yaemon" being given to his sister instead of him.
The eighteenth Ikeda Yaemon is tall, thin, has purple eyes and longish hair falling in his face.
At first he has proven to be a fairly quiet person, but behind that constant smile on his face is a person that turned out to be cold due to his painful past.
Friends & Allies
Some time later, Yaemon sided with Hitotsubashi Nobu Nobu, who suggested eliminating Asaemon and his father to become the next head of the Ikeda Clan. As the 16th Yaemon was found to have released a number of prisoners and had to commit seppuku for the crime, Yaemon had his sister execute his father to make her feel guilty and eventually leave the clan. As a result, he became the next head of the clan.
To serve Nobu Nobu, Yaemon secretly killed the freed prisoners with Kimoarai, who originally opposed the Hitotsubashi Faction. His murders were then rumoured to be tsujigiris, attracting the Shinsengumi's attention. Under Hijikata Toushirou's request, he pretended to be an advisor in the investigation.
The next day, the Yorozuya handed Asaemon back to Yaemon, who recounted their story to the Yorozuya. Knowing that Sakata Gintoki was also a freed prisoner, Yaemon forced him to help the clan. By bribing Mimawarigumi coroners, he then faked Asaemon's death and took all the corpses of his victims on a boat with her and Gintoki, claiming that as a way to get past the Bakufu.
In fact, Yaemon had sold these corpses, Asaemon and Gintoki to the Hitotsubashi Faction as an offer. He was then confronted by Asaemon for his betrayal. There, he revealed to her that Gintoki had indirectly killed her biological father and convinced her to executed him. Yaemon then tried to kill her, but Gintoki foiled his attempt and injured him.
In his last moment, Yaemon killed the Hitotsubashi guards to let his sister escape, believing that she would clean the clan's name. And entrusted Asaemon with the title "Ikeda Yaemon".
As a consequence for his action, he was beheaded by Nobu Nobu. His head was thrown into the river, and was not found by the Shinsengumi.
- Given that "Ikeda Yaemon" is a title, 18th Yaemon's real name has never been revealed.