You,armin,eren,mikasa were in the Shiganshina city because there was a mission beetween the collosall titans you were child-hood friends

eren turned into a titan mikasa had to kill eren to stop all the titans

mikasa: No.. She used her odm gear to kill eren she had tears in her eyes while she glanced at you and armin he saw that your leg was bleeding

Armin was with you he was helping you to calm down Because you were crying

Armin: Please stop crying he wiped your tear