Casshern Sins

The Glass Cradle (1x17)

:

Casshern and the others meet a trio of robotic kids. Ringo makes friends with one of them, a mute robot named Holter. When the three kids go back to their home, which is the facility, they bump into Dio and Leda, where she pretends to be nice to them in order to glean information on Luna and her creator. Leda attacks the kids upon seeing the glass tanks where Luna was said to be born, Casshern fights her. Just as Leda was about to critically injure Casshern, Dio appears and reminds her that he should be the one to kill Casshern and not her.