Kikuchi a one year rental, so he shouldn't require top prospects.
If you are just looking at ERA (4.54) you might not be impressed, but his peripherals (3.99 xERA, 3.58 FIP, 3.40 SIERA and 3.32 xFIP) all say that he has gotten some bad luck and is due for positive regression in the run prevention department.
He's pretty much the best SP option on the market not named Skubal, Crochet, Flaherty or Fedde.