This is an account of how the event occurred: Nobunaga became outraged when he discovered from his daughter, Tokuhime, that Nobuyasu and his mother, Tsukiyama-dono were secretly communicating with his old enemy Katsuyori TAKEDA, so he ordered them to be punished.
この事件は信康とその生母・築山殿が信長の宿敵である武田勝頼と内通していたことが信康の正室で信長の娘である徳姫によって露見し、激怒した信長が家康に信康と築山殿の処分を求めたという事件である。