Talk of the Past is the 202nd chapter of the Rurouni Kenshin manga.
Enishi first reveals the origin of Watōjutsu, the sword style he trained himself in. Chinese warrior generals compiled research about the Kenjutsu the Wakō (Japanese pirates) used whilst raiding the coasts of their land and used it to create Tantō Hōsen, a book that contains the teachings of the new Kenjutsu perfected by the continent, and Chinese-made Nihontōs that were issued amongst the Chinese army.
Enishi then reveals how he came to acquire the Tantō Hōsen. He discloses part of his past, specifically the upper-class Japanese family who found Enishi dying on the streets of Shanghai and adopted him out of pity, giving him food and medical care so he could remain alive. Enishi reveals that he killed the family despite their caring nature and stole their money and valuables, including a copy of the Tantō Hōsen. So enraged and impacted was he by the loss of his sister Tomoe that he couldn't bear the sight of their happiness, which leads Enishi to shift the blame onto Kenshin. This revelation leaves Kenshin and his friends shocked and appalled, making the former begin fighting seriously, much to Enishi's glee.