Whoooooo, Kindaichi! Kindaichi Case Files is probably my favorite mystery series ever, so whenever I read a Kindaichi story, I always treat it as a treat.
The Computer Cottage Murder Case (the Japanese title doesn't translate into English very well), written by Amagi Seimaru, is the third book in the Kindaichi magazine novel series. The setting is fantastic, and the main trick is quite clever. Seimaru also takes advantage of the unique scenario to play some tricks on the reader. The main problem is that the cluing and then actual proof used by Kindaichi is a bit wishy-washy, but it's still a good book.
Also, the killer's name is Takuma. (And now that you're spoiled, might as well read the whole review, right?)