Gunji tsūru (Military Tool)

Eren Yeager never existed. Lurking in the forests within Wall Maria is a strange titan the the Scouting Legion has taken to calling Jäger for it's strange penchant for killing other titans. It is treated solely as an abnormal, and to Hanji's dismay, largely ignored.

But something interesting happens when Trost's gate is demolished by the Colossal Titan-hours into the battle, the strange titan appears and seals the hole in Wall Rose with a large boulder, then proceeds to join the fray. It is then that the military realizes that the titan can be utilized as a powerful tool for humanity, and resolves to use it in the war against the titans.

Original: snkkink.dreamwidth.org/2124.html?thread=1718348