@goodie-bag She's obsessed with getting Tanaka interested in her, and she seems to think the best (or only) way to do that is to get him to see her as an object of sexual desire. Thus all the attempts to let him see her panties, drink her sweat, drink her urine, and so on.
@walczyk Check Gelbooru, it's there. In fact it's how I discovered the manga in the first place. There's a really amusing one where... (NSFW in spoiler!)
Ueno-san gets Tanaka and herself locked in the club room together and suggests having sex. It works too well, with Ueno-san ultimately begging him to stop having sex with her because she keeps cumming. He refuses, saying he's not done yet. Look for stuff by the artist abarai575. You'll have to go to settings -> options, check the box to show all content and then save to see that one. No account required, it sets a cookie for it.
In non-r34 territory, here's a nice image of Ueno-san with really long hair:
@manabi ty!! her with long hair is soo cute. That chapter where she daydreams about having a kid with tanaka and she has long hair lmao gets me laughing
Wh-what just happened? Where did the announcer come from, why was it a tournament? What rules? Wasn’t this about Ta-er Some Kid and Ueno? Where did 13 come from? (The closet I assume) And most important of all… Nice.