Gourmet no Fukurami

Tsutomu Namura has a special condition where due to calorie consumption, he gets a raging hard-on every time he eats. He gets help to cure his irregular erections from Kaiyama and Masaki of human research institute, who find his condition fascinating. Things continue like this until he meet the handsome heir, Haruka Shiga, whose gentle touch seems to help him.

(Source: Tokyo Mangasha, translated)