Complex sentence: It is said that the Boo is based on the wife of producer Takashi Tezuka, who is often shy, but one day, she became very angry at all the time that Takashi Tezuka spent at work.
Split into simpler sentences: It is said that the Boo is based on the wife of producer Takashi Tezuka, who is often quiet. But one day, she exploded, maddened at all the time that Tezuka spent at work.