Just After We Came Down the Mountain, Who Put My Senior Sister and Best Friend into My Arms?

[Invincible going down the mountain] + [Invincible and refreshing] + [Sweeping all the way] The senior sister said that she must marry her best friend The senior sister said that marrying her best friend is a sure thing The senior sister said that only by marrying her best friend can she avenge her family. But the senior sister didn't say that her best friend was so proactive!