Courtesy of the panda's comment section. Multiple posts incoming.
Story starts with Kouta Murata on his way to the nearest Convenience Store, it’s a hot day and Kouta mutters to himself how freaking hot it is, he is drenched in sweat, bitterly remembering the days he wasn’t fat and hot days not being such a pain.
There at the entrance he gazes upon a really hot girl, squatted down eating her popsicle in a really suggestive manner without a care in the world, Kouta muses for a bit on how hot she is, introducing the reader to Chieri Shiina, his classmate; Chieri notices Kouta and greets him and teases Kouta on how long will he keep looking at her exposed panties, she is really upbeat and friendly, Kouta awkwardly stops his fantasies and greets her.
Chieri sees that Kouta is grabing some snacks and ingredients to eat at home, she invites herself to his apartment and grab a bite too, she is hungry, Kouta can’t bring himself to refuse her and Chieri barges in. There at the Kouta’s place Chieri just makes herself at home, talking about how hot that day is and then getting to eat, Kouta is impressed by how much Chieri eats, as much as him yet she isn’t fat like him, Chieri jokes that all the fat goes to her big breasts and big ass, Kouta definitely notices that.
After munching on Kouta’s food, he can cook quite well, Chieri states her business, she asks to be tutored by Kouta, to help her with studies; Chieri’s grades are awful, the risk of her falling back a year is really imminent if things keep going like this, she says she will pay Kouta if he wants to; Kouta first asks why him, sure they are classmates by they aren’t particularly close friends, Chieri responds that it couldn’t be anyone else, Kouta is an honor student, he consistently ranks 1st and at his worst 2nd among all 2nd years from their school, a really big institution that has many 2nd year classes, amounting to 980 students from that year alone.