Nene's HaruYuzu Adventure (ネネのはるゆず道,Nene no HaruYuzu Michi?), Seeing New Facial Expressions...... (いろんな表情がみたいから……,Ironna Hyōjō ga Mitai Kara......?)My Older Sister Should Have Been More Careful (お姉ちゃんはツメが甘い,Onee-chan wa Tsume ga Amai?), My Younger Sister is Currently Jealous (妹はヤキモチやき,Imōto wa Yakimochi Yaki?) and Mitsuko and Glasses-Senpai (みつ子とメガネ後輩,Mitsuko to Megane-Senpai?) are the Omake chapters of Volume 5 of the Citrus manga, which was released on May 18th, 2016. Nene's HaruYuzu Adventure and Seeing New Facial Expressions were part of a leaflet that came with the volume, while the others are part of the volume itself.
Continuing from the previous story, Mei scolds Yuzu for still buying that kind of thing, asking what will she do if their mother finds out about it, all the while Yuzu is worried that Mei is angry at her. Mei then appears to be interested in the game, asking Yuzu to "let [her]..." but doesn't complete the phrase before falling asleep in Yuzu's lap, leaving Yuzu confused.
Sometime before the start of the series, Mitsuko and Maruta are impressed by the headmaster's granddaughter Mei, with Maruta commenting that Mei is very mature for a third year middle schooler, and Mitsuko saying that the next first years will certainly have a mature president too, given her willpower. Maruta then says that she could learn a thing or two from her since Mitsuko is always teasing and testing younger students. Than Mitsuko say the strength of one's heart is unrelated to age Maruta say's it's because of that her younger sister keeps her distance from her this Leave's