The man squees like a six year old when he goes to a space museum. When Sakaki tries to answer it for them, he knocks his friend out, and later when pressed on it, he gets rather angry, and everyone, even high level espers like Kaoru, were quite scared of him.
It's also the prime reason why Kaoru, Aoi, and Shiho are all in love with him, because he was the first supervisor they had that really treated each of them with love and care even by than their own families.
Later on in the series "The Children" become mature enough to make their own decisions without him.
Although initially reluctant, he quickly comes to care for the girls and acts their guardian to the best of his ability. Originally a scientist in BABEL's Research Division, he's conscripted into becoming the Supervisor of "The Children" after he successfully manages to bond with them.