Okay... from the whole book, Ai-chan's friend Barebu-chan lost in a volleyball match and is feeling down, she then seeks comfort from Ai-chan's lethal weapons. Some beating and hot yuri momimomi ensues. Barebu-chan got friendzoned. Ai-chan's sister (most probably) and Barebu-chan's little brother peeks outside. The sister is jealous of Ai-chan for being intimate with Barebu-chan, then realizes that Barebu-chan's little brother resembles her a lot, so she's ready to pounce on him...