He was educated by his grandfather.
Kare wa sofu ni kyōikusareta.
he; him; his; boyfriend
topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis
grandfather; old man; kyogen mask used for the role of an old man
at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although