父(ちち) chichiは wa私(わたし) watashiに ni妹(いもうと) imoutoの no世(せ)話(わ)を()す()る() sewawosuru義(ぎ)務(む) gimuを o負(お)わ()せ()た() owaseta。 My father charged me with the duty of taking care of my younger sister. Literal Father [topic-は] me [to-に] younger-sister's care [object-を] do duty [object-を] imposed. 義務を負わせた uses the causative of 負う (to bear) — 'made me bear the duty.' 妹の世話をする means 'to take care of the younger sister.' familyparentingcausative form (~せる/~させる)
父(ちち) chichiは wa私(わたし) watashiに ni妹(いもうと) imoutoの no世(せ)話(わ)を()す()る() sewawosuru義(ぎ)務(む) gimuを o負(お)わ()せ()た() owaseta。 My father charged me with the duty of taking care of my younger sister. Literal Father [topic-は] me [to-に] younger-sister's care [object-を] do duty [object-を] imposed. 義務を負わせた uses the causative of 負う (to bear) — 'made me bear the duty.' 妹の世話をする means 'to take care of the younger sister.' familyparentingcausative form (~せる/~させる)