He was adopted as a child of Yoritsuna UTSUNOMIYA, moved to Kasama City in Hitachi Province, called himself the Kasama clan, built Kasama-jo Castle on Mt. Sashiro in 1235, which it took about 16 years to finish since he was about 16 years old.
宇都宮頼綱の養子となり常陸国笠間市に入って笠間氏を名乗り、16歳の頃より約16年の歳月をかけて、嘉禎元年（1235年）、佐白山に笠間城を築いて居城とする。