When Kyou’s mother committed suicide, everyone blamed him because he was cursed with the Cat spirit; everyone but Souma Kazuma, who took him under his wing and trained him without judgment. It was Kazuma’s grandfather, after all, who carried the spirit before Kyou, so even though he himself didn’t know what it was like, he was close to someone that did, and had empathy for them both.
Now Kazuma is back, and while he doesn’t show it around the others, Kyou is elated. He assumes he’s to go back to living with his shishou and continue his training. But Kazuma is there for something else. He’s seen Kyou with Tooru, and believes it’s time to tell her the truth about what Kyou is, even if Kyou would prefer to keep running away from that truth.
Kazuma doesn’t see much point in dragging things out. After informing Tooru, he takes Kyou’s arm and removes the rosary of red and white beads that never leaves his arm. Once it’s off, his true form is revealed, and it’s a truly terrifying, monstrous form with a smell to match. Throughout the transformation, Kyou recalls how Akito reacted (how you’d expect Akito to react—with utter disgust and rejection).
He expects the same reaction from Tooru, and while she’s initially frozen in shock, and later nauseous from the sight and smell of him, she still dutifully chases after him, completely forgetting that she just got over a cold!
Assuming she’s only there to have pity on him and offer hollow comfort, both things he’s sick to death of, he tosses her aside, hoping to hurt her enough so she’ll never forgive him. This strategy fails, of course, because we’re talking about Tooru here.
Kyou is weary of Tooru’s comfort (the “lukewarm bath” in which he’d gotten too pruny) because that’s what he got from his late mother: she gave him the rosary, checked his arm dozens of times a day to make sure he was wearing it, and wouldn’t let him outside. He could never trust or accept the love she insisted she had for him because she worked so tirelessly to hide his true form, sweeping it under the rug like it didn’t exist.
Even though his mother told him all the time that she’d die for him, that wasn’t what Kyou needed, or needs. What he needs, and what Tooru ultimately provides, is not an assurance she’ll die for him, but that she’ll live life with him. She doesn’t claim to have all the answers, but she won’t look away or turn away from him, even in his true form.
Tooru fears Kyou never returning to Shigure’s house more than the reality of his true form, so she takes hold of his misshapen limb and doesn’t let go, until he transforms back into human form, and then into his cute Zodiac cat form, and they return to the house together triumphant and to Kazuma’s relief.
In this regard, Tooru has emerged as his new proverbial rosary; one that doesn’t hide what he is but accepts it and is committed to living with him anyway. And however dark the future gets, he’s able to move past his dark past because she’ll be right there facing that future beside him.