軍配団扇: a rigid fan used for sumo or military signaling; a 家紋 (kamon, “family crest”) featuring a gunbai uchiwa design; the field pennycress, Thlaspi arvense

JK: high-school girl

plausible; believable / solemn; dignified; serious

(game of Go) go problems: hypothetical situations constructed and solved in order to practice