The summer vacation comes to an end, and Suguru, Miyuki, Rin and the others return to school. On the very first day, as they are walking to class, Chizuko is nearly run down by an out-of-control car, but saved by a mysterious man who appears, seemingly out of nowhere, and leaves as quicky. Later in the day, the same man, Tou Ryuga, reappears again, as a substitute teacher hired by the school. But later still, at the mention of his name, Mahoro grows uneasy. The reason, revealed in the evening of the same day, is simple: much like Mahoro herself, Ryuga is a combat android, only in the service of the alien invaders SAINT. He attacks Mahoro as she is out shopping, and although Mahoro and Slash gain the upper hand, she feels that rather than being able to defeat Ryuga, she is merely being allowed to survive. Before he leaves, however, Ryuga declares his intention - to challenge Mahoro and make the final determination of which one of them is the better warrior. During Mahoro's active service, her and Ryuga engaged - inconclusively - several times. Now, though, the first step he takes is finding out just what the nature of the relationship between Mahoro and Suguru, whom he knows to the the son of Commander Ryoh Misato, is. It is to this effect that he infiltrates Suguru's school and interrogates his various friends. The responses are nothing but praise - and in the cases of Miyuki and Rin, blushing and mumbling - although unsurprisingly, Saori misinterprets the situation and perceives Ryoh as a rival for Suguru's affections. Later, Slash and Mahoro, who also infiltrate the school, challenge him. Mahoro threatens to fight Ryuga right there and then, if that would mean protecting Suguru. Whether he is truly concerned or simply looking for an excuse to put the battle off is not clear, but he declares that he is unwilling to fight in a location where civilians could be harmed, and leaves.
