Demon core, a spherical subcritical mass of plutonium manufactured during World War II by the United States as a fissile core for an early atomic bomb

戦闘力: fighting strength, fighting ability

先駆者: trailblazer, pioneer

戦闘服: a battle or combat uniform: fatigues, battledress

新選組, 新撰組: Shinsengumi (special police force organized by the shogunate during the Bakumatsu period)

(Buddhism) think on the power of Kannon

赤外線天文学: infrared astronomy

(idiomatic, proverb) be quick on the uptake, understand the whole situation from just a few clues

花一匁: a traditional Japanese children's game that is similar to the game red rover

astronomer