Onimaru: Senjou ni Kakeru Itsutsu no Seishun

During the Onin wars in Japan's medieval Muromachi era, five powerful warriors hire out their services to the highest bidder. Onimaru is the leader; Bo handles demolitions; Saru is as agile as a monkey; Osamu is a cool tactician; and Kiri is the sexy swordswoman. The group gains an extra member when Onimaru rescues Princess Aya who naturally falls in love with him and refuses to go away.

(Source: The Anime Encyclopedia)