On September 16 (September 18, according to another account), Serizawa, Hirayama and Jusuke HIRAMA (Serizawa's disciple who held the office of assistant deputy leader) attended a party at Sumiya in Shimabara, and came back to the residence of the Yagi Family, where they quartered.
9月16日（18日説アリ）、嶋原の角屋で宴会をした芹沢、平山、平間重助（芹沢の門人で副長助勤）は夜中に屯所の八木家に帰った。