Kentaro is a bundle of contradictions. To the ladies, he is gracious and generous. To rival men, he is an obnoxious, stuck up punk with an inflated sense of self-worth. He is perhaps the most eligible bastard in Amber, the result of an adulterous fling between Wakaba and King Rinaldo of Kashfa. Certain rumors whisper Wakaba ensorceled Rinaldo, while others say he did something to her. The exact chain of events remains a mystery, but it's clear he was concieved during the Annadil Crisis. He dwells in Amber, tending to reject his Kashfan heritage, although his father wants him to come home soon to prepare for the day when he must take up his duties as King of Kashfa. The fact that his step-mother, Queen Coral, hates him hasn't made him eager to go home.
Among the oldest of the Herald Crisis generation, he is quite skilled in the social graces, having attended Ohtori Academy. He is more known for strength of mind than of body, though he is a notable fencer and adept at horseback riding. He's known to have some skill at alchemy, having studied with his mother, and to throw very good parties, probably due to his training from King Tylor.
Kentaro is known to have a magical mansion which follows him around shadow. There is always a formal ball about to start, and invitations to his parties there are much in demand.
Kentaro's heroic deeds during the Herald Crisis are too numerous to mention (well, not really, but I'm lazy), but can be found in the UnS Timeline.
For a few years after the Annadil Crisis, he dated Anna Unruh, the assistant librarian. Until she dumped him in 1338 after catching him with another woman.
In 1343, Demetrius IV finally snapped. He executed his daughter, Princess Alexandra, who had been seeing Prince Kentaro. Kentaro responded by calling out Prince Alexander, Demetrius' favorite son, to a duel. Too proud to refuse, Alexander went to the duel, and Kentaro chopped him into bits. Demetrius IV demanded Kentaro be turned over. Tylor replied that while he extremely disliked duels, they were, unfortunately, legal under both Amberite and Uilan law, and that perhaps he shouldn't have executed Kentaro's lover for no good reason. This led to the War of Demetrius' Son, in which Prince Kentaro fought nobly and well and rather angrily.
Kashfa was on the verge of intervening in the War of Nicephorus in 1390, when the riots, disorder, and eventual civil war known as the Fronde broke out. A combination of noble disaffection, dislike of Queen Coral, financial crisis and a massive crop failure led to the near collapse of the Kashfan state. Amber refused to intervene, arguing Queen Coral had 'meddled in Amberite Court Affairs'.
Nearly twenty years of anarchy and bloody civil war followed. The end came only when Prince Kentaro, to the surprise of many, came to the aid of his father, and somehow convinced Shinobu Major to sign on as a 'volunteer'. Shinobu Major wiped out six major Kashfan noble houses to the last man, woman, child, and dog, and soon had the rest reduced to quivering fear. Kentaro has become closer to his father as a result of this, and even Queen Coral has softened towards him, although she still hates his mother, Wakaba.
The Kashfan monarchy became much stronger, but is also now dependent on Amberite aid to survive in the face of resentful nobility and angry peasants.
Kentaro is known to be closer to Telemain than to Telemain's parents, and remains friendly with Sumire, though there's always a shadow over them when they meet. He's had some friendly dealing with Moonshade of late, concerning their joint interest in conjuration. He's also known to have helped train Yomiko, and to be on very good terms with her. Kentaro seems to enjoy conjuring Cone People and turning them loose to watch Setsuna freak out. He has been known to call Miroku 'Manwhore', which Miroku responds to by calling him 'Pot-Boy'. He seems to get on well with Kaname and Aburatsubo.
Prince Kentaro now serves as Ambassador to Therin.
Kentaro is currently in Amber, recovering from an attempt on his life.