Slash is known as a "support mech" and assists Mahoro during combat. He has the form of a panther and can be summoned at any time by Mahoro. Although he can speak, his mouth never moves except during times when he expresses emotions. Although used for combat in the past, he often now acts as a guard dog around the Misato residence and a friend to the Misato's dog — a role he was not thrilled to take in the beginning.

He is friendly but tough and will lend a helping paw when asked. Although Mahoro is Slash's master, he will now take commands from Suguru: since Suguru is Mahoro's employer, he is also her master and thus Slash's master as well.
(Source:Wikipedia)