In Alisa's storyline, his wanzer is the Shangdi 1, and he starts off with a Rifle.
In Emma's storyline, he is an enemy.
In Alisa's storyline, Kazuki, Ryogo, and Alisa meet him at the Yokosuka Military Base after the battle with Purple Haze. He saves them from both Purple Haze and JDF Special Forces, and later helps them escaping Japan.
It is later found that his mission has changed and he is ordered to bring Alisa to Ravnui embassy in Shanghai. His mission changed after knowing that Alisa is one of the scientists related to MIDAS. In Ravnui Embassy, he meets Lukav Minaev, who brings Emma Klamsky with him. The meeting only creates a degree of desperation in him, as Lukav announces that he is no longer loyal to Bal, and in doing so, kills him.
After that, Liu departs from the team for a while. Upon rejoining, he swears to take revenge for Bal's death.
In Emma's storyline, Liu is an enemy. The player encounters him three times: once in Japan and twice in DHZ. In the DHZ encounters, Liu makes use of the Zeros.
After the chaos in Ravnui Embassy, Liu and Bal come to the missile silo base to reclaim Emma and Alisa from Lukav. A battle occurs between Liu and some Imaginary Numbers, and amidst the crossfire, Bal meets his death.
After Lukav's defeat at the missile silo base, Liu appears once again with damaged wanzer, intending to kill Emma and Alisa (because Bal has died, and he has no intention to continue using them). The player must defeat him before he reaches the area where he can kill them. This is not a difficult task for those using high movement Wanzers (equipping them with Grapple M1 legs or their equivalents, for example) to block his movement while attacking him.
Prior to his death, he reminds the team that all Imaginary Numbers are dangerous and must be defeated.