Looks like it's going to be an exciting episode.
Episode starts off with Choco cleaning the sink. She gets soap bubbles all over herself, and ends up washing the clothes and hanging them up to dry. While they're drying, she decides to take a nap.

Yeah uh, I'm all out of witty comments for now.
Meanwhile, Chitose is hanging out her clothes to dry. Later, as she's folding them, Choco comes and asks if she wants to go shopping together. Chitose says that she needs to fold clothes first, and Choco volunteers to help. Choco picks up one of Chitose's bras and asks her what it's used for. Despite being very embarrassed, Chitose obliges and lifts up her shirt. Well naturally Choco now wants a bra …and wants Haruma to go with her to get one, no less. Token embarrassing situation much? Haruma is opposed to the idea but eventually agrees.

Speaking of which, where ARE Haruma's parents anyway? Hmm…
Haruma is rather embarrassed to be in the lingerie shop, it couldn't get any worse unless someone he knew saw him there. Ah, too bad for Haruma… Ayano-san shows up to change the shop's floral arrangements. Despite Haruma's fears, though, Ayano seems to be rather oblivious to the implications.
Back at home, Choco immediately begins to try on her new garments. But… she has a little difficulty.

Cue for perv-Shiki?
Later that night, Chitose hears a loud thump and walks out to see Makoto lying drunk at the bottom of the steps. As Chitose tries to wake her up, Makoto suddenly begins to assault Chitose's breasts (again). With Haruma's help, Chitose manages to put drunken stupor Makoto back to bed.
The next day, Choco, Chitose, and Makoto gather for a meal. They're having a good time, and going along with the theme of the episode, their topic of conversation turns to lingerie. Choco says that she is not wearing any underwear, because she only has one pair and she wants to make it her 'game underwear'. (Game underwear is the underwear that girls wear only for the guy they like, or something…idk. It's written in her instruction manual, apparently.)

Someone really needs to confiscate that thing.
Chitose and Makoto are pretty shocked, asking her who she has in mind. Choco innocently replies, "Onii-chan."
On the way back from shopping, Choco and Chitose meet Haruma, who offers to carry Chitose's bags for her. Chitose then invites him to dinner. That night, Choco writes about how she has made her first underwear her 'game underwear', but is unsure who to have a 'game' with.