The O-Chesra appears in two missions where its destruction is required for victory. It first appears during the first encounter with the invasion fleet's forces after Wein and Lushati's rescue where Rowil introduces himself. The subsequent mission has the Elsior and the Angel Wing circling around the area to attack Rowil directly while most of his ships were ahead of him.
In his second and final encounter, the Elsior and Angel Wing confront Rowil at his forward base where he had just issued for his fleets to return to defend the base. The O-Chesra's destruction and Rowil's death however do little to ease the team as they had anticipated the rest of his fleet as enemy reinforcements to appear but had mysteriously disappeared.
In all cases, the O-Chesra is a deadly vehicle that sports both high armor and weapons and should not be allowed near the Elsior. It's range is close to that of a destroyer and can easily wipe out larger targets on its own.