According to 'Kinrin-ji Temple's Genealogies of TOSHIMA' and 'Yasumitsu's Genealogies of TOSHIMA' created by Yasumitsu TOSHIMA who was a hatamoto (direct retainer) in the Edo period, Asatsune was the oldest son of Kiyomoto and his lineage became the main branch of the Toshima family, but his name was not described in 'Genealogies of Toshima Miyagi' by the Miyagi family who was the clan's hatamoto (the lineage of Kiyoshige KASAI was to be the main branch of the family in this genealogy).
朝経は江戸時代に旗本豊島泰盈が作成した「金輪寺本豊島家系図」「泰盈本豊島家系図」では清元の長子とされ彼の系統が豊島氏の嫡流となるが、一族の旗本宮城氏の「豊島宮城系図」ではその名が現れない（こちらは葛西清重の系統が嫡流になっている）。