OPPAI Academy: Big, Bouncy, Booby Babes!

Takumi Kazuya is just an average student at Iseumi Academy who has been suffering from delusions of grandeur since a young age. He dreams of conquering the literary world by becoming a best-selling erotica novelist and having his works adapted into anime. One day, when Takumi is taking his usual two-hour bath while thinking up plots for his new novels, his sister gets upset with him. This is no unusual occurrence, and normally the tantrums of his sister, an aspiring eromanga artist herself, only serve to amuse Takumi. This time, however, she decides to turn up the bath thermostat to the maximum temperature. It was meant to be nothing but a silly prank, but then alarms start ringing—the kind you might hear in a disaster movie—and the bathtub starts making ominous noises, as if it's about to explode! Takumi's life starts flashing before his eyes, and before he realizes what's going on, he finds himself enveloped by nothingness...
"As he struggles towards the light, trying to find an exit, he suddenly falls into a large body of water. Unlike the small bath he was in moments ago, this appears to be a large, public pool, and... it's filled with busty girls in bikinis!? This must be heaven!
Taking a closer look, he notices that not all the girls are human. They appear to be from a variety of species, and their reactions to the sudden intruder are just as diverse as their looks. Some even start summoning magic circles and shooting arrows of light! If this were a light novel, they would probably challenge him to a duel after seeing them in their swimwear, and his maxed-out luck stat would allow him to win and instantly earn their affection... Or at least, that's what Takumi fantasizes about as he narrowly escapes from the otherworldly pool into which he has just reincarnated.
Said pool turns out to belong to the prestigious Yggdrasil Girls' Magical Academy, and Takumi will be its first male student. Will he be able to conquer the hearts of the entire academy!?"

[From Steam]