Since Sadanobu KANO, head of the Kano family, did not have a child when he fell into critical condition in 1623, Naganobu KANO and Yoshinobu KANO, two major figures in the family, had discussions in which they decided to adopt Yasunobu, then 10 years old, as Sadanobu's child and have him take over the Soryo family (the head family).
元和9年（1623年）危篤に陥った宗家当主の狩野貞信には子供がいなかったため、一門の重鎮に当たる狩野長信と狩野吉信の話し合いの結果、当時10歳であった安信を貞信の養子として惣領家を嗣ぐことが決められた。