After Nobunaga ODA was killed at the Honnoji Coup in 1582, Kokei conducted a memorial service marking the 100th day after Nobunaga's death by Rikyu's request, and also served as officiating monk during Nobunaga's funeral which was held by Hideyoshi TOYOTOMI.
1582年（天正10年）織田信長が本能寺の変で殺害されると、利休らの依頼を受けて百ヶ日法要を行い、豊臣秀吉が信長の葬儀を行った際にも導師を務めた。