Call It What You Want (AO's Cavern) - S2.E2

The G-Monster continues its attack on Iwato Jima, and with Gazelle's help Ao pilots an IFO being transported by the Japanese Navy and uses it to defeat the G-Monster, his hair changing color to turquise in the battle, all while Team Pied Piper pilots watch, realizing that the IFO is the first ever model made.