Masamoto Tenno was the first-born son of Masamoto Takeshi and older brother to Masamoto Yamato. He was murdered by the Ninja Dragon Eye as revenge against Masamoto. After Tenno died, Yamato was pressured by his father to measure up to his brother, hard for someone who was younger than him by a few years.

When Jack arrived in Japan, it happened to be the anniversary of his death, therefore, Masamoto took it as a sort of an omen that Jack should be adopted by him.