His motive was like that of Chinese surnamed Chang who emigrate to Japan, who change their name to Nagayumi (which in character form is [長弓], the combination of which two characters makes the character for Chang [張]): All want to make clear that they have not forgotten their Chinese ancestry.
這就像姓張的中國人入籍日本，改姓長弓一樣，表示並沒有真的「背祖」。