Hiroo, gifted with academic ability from an early age, was called a prodigy, and ascended Mt. Hiei at the age of 15 and joined the first Tendai-zasu (head priest of the Tendai sect).
幼時から学才を発揮し神童と呼ばれた広雄は、15歳で比叡山に登り、初代天台座主（てんだいざす）義真に入門。