Null Peta: Doki♥ Nurunuru Petapeta! Mizugi-darake no Oneechan Taikai!

ぬるぺた ドキッ♥ ぬるぬるぺたぺた! 水着だらけのお姉ちゃん大会!

Extra episode included in the Blu-ray/DVD release.