Battle Spirits: Shounen Gekiha Dan  

Battle Spirits 少年激霸弹, バトルスピリッツ 少年激覇ダン, Battle Spirits Season 2, Battle Spirits 2

Dan Bashin is a 12-year-old boy who is transported to an alternate world called Grand Rolo by two enigmatic siblings named Yuuki and Kajitsu Momose. In this new realm, he discovers that he is one of the selected core soldiers responsible for carrying the essence of the red core. Along with his fellow warriors, Dan must battle against Otherworld King, who has been oppressing Grand Rolo's indigenous inhabitants.