Interesting card, pretty flavourful and creative.
However, the mechanics does not reflect any red at all. If anything, make it Blue/Black instead. Black compliments the regeneration and the destroy abilities. B/U's philosophy of secrecy and manipulation also ties in well with Yuki anwyays. Also, the max hand size increase feels a bit tacked-on. Not necessary, imo.
As well, rather than the depletion counter abilities, I suggest replacing it with "Tap: Put 3 time counters on target permanant and it gains vanishing", or somewhere along those lines. You can replace the tap with a mana cost if you want to as well.
Anyways, good job! The card is very well done overall, feel free to share any others you came up with.