Takumi suggests he and Ao study together some time, but Ao is against it because she knows what such things can lead to. However, Takumi says “pretty please,” so she grudgingly agrees, and orders her first pair of silky panties so that if and when Takumi makes his move, she’ll be prepared.
Then she goes to Takumi’s and they’re both alone together, and there’s never an if or when. One, two hours pass, and Takumi only seems interested in…studying. Even when they make a wager for the loser to do whatever the winner wants, he just wants her to make her lunch again.
This steams Ao’s beans, because she went out of her way to wear sexy panties for the occasion, and Takumi is so pure and dense he can’t take the hint that it’s okay for him to make a move. It either never occurs to Ao that SHE should make the first move instead, or she, like Takumi, is too inexperienced and timid and afraid of coming on to strong.
So Takumi fails to resemble anything like the crazed sex beast of her imagination, and ends up a lot more like…well, like her. Only he likely wore comfortable boxers with the knowledge she’d never see them, while she ends up with a stomachache due to being unaccustomed to low-riding underwear. If she wants…that from Takumi, simply waiting isn’t going to cut it. She’s going to have to say or do something, and deal however he ends up responding.