Radical Blood Monster
ラジカル・ブラッド・モンスター
An aspiring writer named Sagara Yuichi becomes involved in a convenience store robbery. Instead of fleeing, he stays behind to observe, which leads to him being stabbed. On his deathbed, a mysterious man appears, stating it was fate. Hours later, Yuichi wakes up naked beside this man. The stranger explains that Yuichi's blood is classified as "S-Class" and declares himself Yuichi's permanent "partner." Yuichi must now come to terms with this unexpected situation.