イヌミミとネコミミが当たり前に存在する世界。
舞台は小さなイヌネコ診療所。
診療所の院長は人間の女医、クレイン先生。
情緒不安定、体調不良を訴えるネコミミたち。
主人公ジャックは気のいい大型種のイヌミミ。
その役割は助手兼雑用。
ちなみにここに来るまでの記憶はなく、
先生への恩返しに診療所の手助けをしている。

先生には遠慮なしに、こき使われ、
入院患者たちにはわがまま放題を言われながらも、
愛すべき彼は穏やかな毎日を送っていた。
ただし患者への治療法以外は…

治療方法は主に患者との性行為。
先生の出すカルテに従う場合、患者の希望に任せる場合…
ふと疑問に思うときもあるが、
これは治療なのだと自分に言い聞かせる。

それに…もちろん自分だって発情するわけで…
まぁ…とにかく、
過去のない彼には、この診療所が全てなのだし。

I am Tachibana Eiji, a regular transfer student. Everything was going fine at my new school, but I was in for a shock one day when I discovered the class president Rumi and my classmate Natsuki having sex in the school infirmary! Not only that, it turned out that Rumi was a futanari - a hermaphrodite with something between her legs I wasn't expecting to see. That evening when I got home and got a call from Rumi to come and meet her, I knew it couldn't be good - but the first thing she said was, "won't you join us?"

According to her story she'd been a futanari from birth, and because of this had an unquenchable curiosity regarding the ways of sex. She'd gotten to the point where having Natsuki as a sex partner wasn't enough... she told me she was planning to train our classmate Shizuko as a sex slave! Shizuko, a neat freak famous for her disike of her male classmates, had let it slip to Rumi that she was secretly very curious about sex as well...

Faced with no other options, I had no choice but to accept Rumi's request to join her and her comrades in their erotic schemes... and from that moment I was bound to these cute and "ecchi" kitties in their catgirl alliance!