My Friend's Little Sister Has It In for Me! Volume 9 by mikawaghost

Midori’s confession was the final push Akiteru needed to work out his feelings. But all that’s gotta wait, since he’s still in the middle of the class trip! Mashiro goes on offense and invites Akiteru on a date to Tenchido Eternaland, a Kyoto theme park. Iroha’s mother greets them with open arms...but wait, how’d Iroha end up at the park too? Add Iroha’s peskiness Akiteru’s list of problems, just when he was hoping he could catch a break. Aren’t theme parks supposed to be fun?!