Akira is married to Hina, who is the younger sister of Sato. Yukio is Hina's only nephew, who is the son of Sato. If it is Hina's birthday and Akira is planning a surprise party, would Yukio be responsible for inviting Sato?

Respond very briefly.
Hina, being married to Akira, is considered part of Akira's immediate family. Sato is Hina's older sibling. Yukio, being Sato's son, is Hina's nephew and also Akira's nephew by marriage. If Akira is organizing a surprise party for Hina, Akira would typically take on the responsibility for the guest list, which includes inviting close family members. As Yukio is the nephew and not the primary organizer, he would not be responsible for inviting his parent, Sato, unless Akira specifically delegates this task to him. It is common for the organizer of the event, in this case Akira, to extend invitations to immediate family members themselves, especially for a significant occasion such as a spouse's birthday, ensuring that important family members like Sato are not left out.