It is said that Sadatsuna presented the Seigan-ji Temple a big nationally-rare iron sotoba (a tall, narrow tablet set up behind a grave for the repose of the dead) (possessed by the Segan-ji Temple in Utsunomiya City and designated as national important cultural property) to commemorate the 13th anniversary of his mother's death.
貞綱は亡母の13回忌に全国的にも珍しい巨大清巌寺鉄塔婆を奉納した（宇都宮市清巌寺蔵：国の重要文化財）と言われている。