Because he couldn't manage to raise the expense for redeeming Miyuki Dayu, the concubine of Isami KONDO (It seems that there is no link between two issues; redeeming Miyuki Dayu was attempted at the different time from Kawai's purge).
近藤勇の妾の深雪太夫を身請けする費用の捻出がうまく進まなかったため（深雪太夫の身請けと河合の粛清の時期に整合性がないため関連性は薄いとみられている）。