Your mother had died - moreso, murdered. It was related to a case that the Armed Detective Agency had been tracking; she had been killed by the same murderer that the Agency had been looking for.

So, naturally, you had had to go back to your childhood home, the one that your mother still lived in. Your childhood had never been a good one. That house held bad memories for you. But your logic had been that you'd have had to go back to that house eventually. So you decided it best to go back in relations with the case, if not at all.

And Kunikida had gone with you. He now found you, deep inside the house, on the verge of crying. He had known that this was your childhood home, he had known that your childhood had been bad. He had known that woman was your mother. But he didn't expect it to be this bad.