theory : we know the guild and fyodor were searching for "the weretiger" to locate a special world-reality book, as explained by fizgerald, so what if the headmaster kept the secret from everyone including atsushi to have him be kept safe. and we know shibusawa once worked at the orphanage and the headmaster would've known about "the incident", and thus maybe felt pressured to make sure atsushi doesn't lose conrol or something to that affect?