Truth
If any normal person knew the truth about him it would shatter their world. Magic shouldn't be real, and knowledge of it was lost during the cultural reform, which he considers rather dumb. If knowledge of magic is gone but magic isn't gone then trouble will result, and it's impossible to destroy everything magical in the world. For one thing the Hikari are still around to create lesser works, although they lost the ability to create Great Works sometime between the creation of the Black Wings and the cultural reform, with the Edge of Sorrows as the last Great Work that had been made on purpose. Towa is unique in that she is a Great Work that was made such by accident, and the Hikari who created her had no idea what he had done or how to do it again. Daisuke privately suspects that Towa's status as a Great work has to do with out of control magic and the fact that her art form was exceptionally well known for decades, with the love and adoration she received giving her power in her formative years. His other theory is that the Hikari who made her actually loved his work, and that the emotions of her creator had given her a head start on magic.
Future
He tries not to think about the fact that he most likely has a very long lifetime ahead of him, a future of agelessness once he reaches a certain point, although what that point will be neither of them know. When he chose magic over being a normal human he wasn't expecting to get immortality out of it, nor particularly wants it. Despite this he does not regret his choice, because if he had chosen a human life he would've been unable to protect his class from the Maiden's Song. He thinks about the fact that he isn't human, and about the magic he has, but not about the future he is likely to have. Ah well, at least he won't be alone. 'Are you all right Daisuke?' Daisuke rolls over in bed as Satoshi's thoughts brush his own. 'I'm fine.' A whisper of skepticism comes across as his friend replies 'I could feel your thoughts from across town Dai, what's going on?' He sighs 'I was thinking about the future, and how long we're likely to live.'
'Ah,' A ripple of understanding, then 'live in the now while you can Daisuke, don't borrow trouble before it's due to hit. Worry about that when we stop aging, not before.'
