Isshin is a fool. He's intelligent when he wants to be, a fierce combatant when he's properly motivated, but still a fool.
Only a fool would insist on hiding his son's heritage from him, despite knowing he could see what others can't. Only a fool would fail to notice the difference in Ichigo after Masaki's death.
The other children at his school have noticed, the teachers have noticed, but the boy's own father hasn't. Really, Kisuke thinks as he watches the boy loiter outside the shop, Isshin should know better. The boy saw a hollow devour his mother, at the very least that should be a source of trauma.
Should being the key word, oddly enough. Kisuke had expected to see his grades slip, to find the boy with bruises and scrapes from fights. Ichigo should be grappling with doubt and fear and guilt, with all those inconvenient emotions.
But he hasn't, and that's enough to make Kisuke look closer. There's no strange changes in his schedule, nothing to warrant concern. Ichigo has gone back to the dojo and even managed to wrangle Isshin into paying for sword fighting lessons, but that can be explained away. The boy is young and excitable and human. Kisuke can easily see him becoming enraptured with another way to protect.
Ichigo may not be displaying the classic symptoms of grief, but there is enough oddities to worry Kisuke. He may not be entirely familiar with human psychology, but he knows enough to be aware that talking to thin air is a problem.
The boy doesn't flinch or startle when Kisuke steps out of the shadows, and he marks it as yet another oddity to be investigated.
"Urahara-san," Ichigo greets him stiffly, "I wanted to talk."
"Of course, Kurosaki-san!" Kisuke snaps his fan, hoping to get a laugh or a smile out of the boy at the use of the honorific, but all he gets in response is a raised eyebrow. How annoying.
Ichigo settles onto a chair, hooking his legs under it and leaning his elbows on the table.
There's silence for a moment, the boy tracing patterns onto the table with a finger as Kisuke waits for him to speak.
"You're a shinigami," Ichigo finally speaks up, looking at him with determined eyes.
Well. For the first time in quite a while he's caught off guard, only barely managing to keep his eyes from widening.
"Was," Kisuke corrects him.
"But you're not human, not really."
"No, I suppose not," Kisuke agrees, lowering the fan and making sure Ichigo sees his wry smirk.
"You're like dad," Ichigo continues, looking as though he's about to say more before snapping his mouth closed.
"And how do you know this? I can't imagine Isshin telling you." He knows he's right when Ichigo's eyes flash, hands tightening until his nails bite into the palms of his hands.
Ichigo pauses, chewing at his lower lip in thought, before looking up at Urahara.
"You can't tell anyone. You can't tell dad. You can't tell the shinigami."
"Cross my heart and hope to die," he replies with a wink, smirking when Ichigo scowls.
"I'm serious!"
"What makes you think I'm not?" Kisuke retorts, leaning back in his chair and staring down Ichigo until he looks away in embarrassment.
Ichigo opens and closes his mouth, seeming to wrestle with himself, before finally speaking.
"Shiro told me, about shinigami and hollows and all that."
"And who's Shiro?" He replies, eagerly awaiting what's likely the explanation for Ichigo's strange behavior.
"My," Ichigo hesitates, "my friend."
Kisuke waits patiently for him to continue, the boy obviously having trouble forcing his next words out.
"He's my hollow." His eyes do widen at that, staring at Ichigo with an expression that can only be described as poleaxed.
This explains why Ichigo's been acting odd, true, but it only raises more questions in return.
"And why," Kisuke asks as he looks at Ichigo, "would someone with a hollow in their head come to a shinigami?"
"I," Ichigo stumbles over his words, "I need training, and I don't want dad to know."
"Training?"
"My reiatsu keeps attracting hollows, and Shiro helps me when they get to close, but I don't want to always fight."
Kisuke had thought it curious, that Karakura had less hollows despite the usual incompetence of the shinigami sent. He resists a laugh at that, at a mostly human boy doing what no one else could.
"Alright, Ichigo," he agrees with a smile, "I'll help."