Honoo no Haramase Oppai: Ero Appli Gakuen 2

Our protagonist, Majime Masato, is an extremely average and extremely lewd second year student at Ichisakura Academy. His reputation as a pervert precedes him. One day, he saves a black cat named Shami who gives him a magical "smartphone of love" as a gift. He levels up from being a lowly perverted student to being the most perverted student in the whole world! Ichisakura Academy ranks in the top three in the nation for average female bust size, so Majime has quite a selection to choose from!

However, Shami comes to tell him that his phone won't last forever, so Masato decides to go all in and accomplish his crazy sexual fantasy of impregnating every girl in the school!