Shikonin ~Ass-Pussy Training by Longtime Friend's Huge Dick~

I was mercilessly prepared for my mission by my sadistic friend.

Ai, a ninja who can't get the job done. Ai is assigned to be a "manslut" due to his poor performance.

Ai's longtime friend, Mimei, is assigned to train Ai to become a "useful" ninja.

The sadistic Mimei continues to train Ai, but his true feelings lie in his obsession.....

Overall, it's a happy ending.

(Source: DLSite)