Tenken is the manifested spirit of Sajin Komamura's Zanpakutō that is seen during the anime-exclusive Zanpakutō Rebellion and the subsequent Tōjū Campaign.  Despite his mighty and intimidating appearance, he appears to be a very calm individual, having yet to lose his cool. According to Gonryōmaru, Tenken seems to be incredibly shy, like his Shinigami wielder, which explains why he doesn't normally talk. So far, he has only spoken once, saying the word Bankai in a deep echoing voice.  (Source: Bleach Wiki)

Ichigo Kurosaki is a rather normal high school student apart from the fact he has the ability to see ghosts. This ability never impacted his life in a major way until the day he encounters the Shinigami Kuchiki Rukia, who saves him and his family's lives from a Hollow, a corrupt spirit that devours human souls. 
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Wounded during the fight against the Hollow, Rukia chooses the only option available to defeat the monster and passes her Shinigami powers to Ichigo. Now forced to act as a substitute until Rukia recovers, Ichigo hunts down the Hollows that plague his town. 




[Wiki (jp)](https://ja.wikipedia.org/wiki/木村雅史)