Unlike adoption, however, Yushi was based on a contract and had a weak connection, and a child's surname was not changed, so it was rather a fictitious parent-child relationship (in which a parent became guardian in many cases).
ただし、養子縁組とは違い、契約関係によって成立し、子供の姓は変わらないなど親子関係の結びつきが弱く擬制的な側面（その子の後見人となる）が強い。