Why!? The Night Before the Decisive Battle. Taneshima's Returned Favor.

なぜか!?の決戦前夜。種島の恩返し

nazeka!? no kessen zenya. taneshima no ongaeshi

Sota tries to hide the fact that his sister Kozue is the drunkard who regularly visits Wagnaria by not telling Poplar that Yamada and Mahiru slept over at his house. Poplar eventually finds out and his secretiveness upsets her. In order to make it up to her, she gets him to agree to go on a date with Mahiru. Yamada and Poplar take drastic measures to cure Mahiru's androphobia before the big day but they prove unsuccessful.