Well for the most part, especially in PMK we are presented with Susumu being an instrumental factor to the Ikedaya-affair. Suzuki Tooru throws some “doubt’ into his participation into the raid itself.
After the succesful raid of the Ikedaya, the Shinsengumi were awarded monetary compensation. I won’t go into the details here as this post is about Susumu. According to Yagi Tamesaburou, the men got red drunk with Sake and ran to Shimabara shouting “It became a Daimyo! It became a Daimyo!” (Note I went with the literal translation, another translation would be, “It became a large name”.), there were 34 men in all who received the merit award, but surprisingly Yamazaki’s name is not at all mentioned O_O It is said that Yamazaki’s contribution leading to the Ikedaya raid was preeminent. Where he is thought to have done an advance search and was their “inside” guide, playing the role of the unsung hero.
In Shimada Kai’s diary Yamazaki is mentioned along with Shimada, Asano, Kawashima as the group to do the advance search. All three except for Yamazaki received a merit award. Kondou in one of his letter mentioned placing only three spies, it is not sure whether Yamazaki is among these three spies. (But Shimada Kai and the other two got the award so that makes three)
On the night of the Ikedaya riot according to Nagakura’s “Shinsengumi Tenmatsuki” the exposure of 20 or more Choshu patriots was a chance occurence, there is no mention of a prior search or guidance of Yamazaki Susumu. With the way Nagakura had described the Ikedaya raid, it also throws a doubt whether Yamazaki Susumu was even involved at all.
There is some who think that the Miburoshi Shimatsuki by Nishimura Kanefumi, which describes Yamazaki Susumu’s activities in the Ikedaya, is fiction. This is because of Nishimura writing that Yamazaki Susumu died in the battle of Toba-Fushimi, while there is another account where Hayashi Shintarou (name?! I believe he was Shinsengumi) visits Yagi Tamesaburou and tells him that although Susumu was a courageous man, he was shot in the body and was forced to board the ship Mt. Fuji along with 44 comrades. He died while sailing near Kishuu (place?) because of his wound. His cadaver was wrapped in a futon and weighted by four cannon bullets (balls?) and sunk to the sea. Hijikata was said to have read the codolence message as Kondou’s shoulder was still in bad shape and that people cried a lot. I assume the whole group… T__T
Anyway, Nishimura does mention that Yamazaki Susumu’s name was omitted from the merit awards… So Nagakura doesn’t mention Susumu at all with regards to the Ikedaya while Nishimura says otherwise.