Naturally, Tomo is shocked and feels betrayed by the fact she’s only now hearing about Jun and Misuzu going out. Misuzu only kept it from her because she herself preferred if it never happened. Jun asked her out on a whim, and they dated for a grand total of three days. I’m also convinced Misuzu calls it “youthful indiscretion” since that was practically Hidaka Rina’s character Yume’s catchphrase in My Stepmom’s Daughter Is My Ex.
We also learn that Jun avoided Tomo for the entire first year of middle school, and they didn’t reconnect as best buds until he’d dumped Misuzu. Like her, I don’t think that’s a coincidence. It’s likely that Jun asked Misuzu out because he was trying to avoid the fact that he had developed a thing for Tomo, and wasn’t ready to deal with that.
It’s become ever clearer that Tomo is not the best judge of whether Jun sees her as a girl, since the moment Jun learns that she’s in the boy’s karate club, he freaks out, and is particularly hostile towards Misaki. The two end up bonding (somewhat) on a bus ride when Jun admits that in a fight with rules like karate, he can’t beat Tomo either; she’s “too incredible”.
The next day after school, Jun asks if Tomo is free to hang, but she has plans with Misuzu and Carol to get tea. She runs into Ogawa and Mifune, who are harboring some very confusing feelings about Tomo and are so shocked by the sight of her in pants that they flee. Misuzu warns Tomo that she can’t keep blowing him off, and shouls arrange a date.
Tomo is dubious that Jun will be as pliant as Misuzu predicts, but when she does take the initiative and ask if he’ll hang, his reaction is just like that of a golden retriever who found out he’s going on walkies. Misuzu and Carol decide on the best outfit for Tomo, one that’s a bit girlier than her usual garb, but not so girly she’ll be too self-conscious.
The resulting white pullover, gaucho pants, and white sneakers ensemble really hit the mark, though Jun doesn’t let Tomo know how cute she looks, the swine. What he does do is let the two of them slide right back into their normal hangout routines: going to the batting cages and bowling. Each time, Tomo is certain she can’t hit a 160 kph fastball or roll a 16 pound ball, but in both cases, she’s still right on Jun’s level.
She then asks Jun if they can go to karaoke, and immediately acts like he said know when he actually said yes, leaving Tomo in a bit of a spot, as she hadn’t thought any further than “going to karaoke.” The place is a lot more intimate than she expected, and since the only songs she knows are children’s songs, that’s what she sings … and Jun records her.
The thing is, he’s not recording for blackmail purposes (though the minute Misuzu and Carol hear he has footage of her singing they want it). He was thrown off how…different Tomo was that day. But not thrown off in a bad way. Clearly it’s a side of Tomo he’d like to see a little more of.