Sonoa gets drunk and ends up living at Tachibanakan. Yuu gets everyone to have a welcome party for Sonoa, so they meet by the riverside in appropriate outfits. Yuu has water guns waiting for them, and has everyone enter a "Water Gun Survival Game".
How are we going to have 
a welcome party here?!
Wie wollen wir hier
eine Party veranstalten?!
¿Qué clase de fiesta haremos aquí?
¿Qué clase de fiesta haremos aquí?
Comment tu veux
qu’on fête ça ici ?
E come cavolo facciamo
 a fare una festa qui?!
Como vamos ter uma festa
de boas-vindas aqui?!