What other game created by Silver Age Sentinels is referred to by the acronym BESM?
Silver Age Sentinels: Silver Age Sentinels is a superhero role-playing game (RPG) published in 2002 by Guardians of Order, creators of "Big Eyes, Small Mouth", an anime-themed RPG. Big Eyes, Small Mouth:  It is frequently referred to by the acronym BESM.
Big Eyes, Small Mouth