My wife and i rented 2 touring bikes from sparks cycling for our self-directed 10 day touring trip around Hokido.  

Tldr: Sparks cycling and Daisuke are great to work with, provide excellent service and excellent bikes for your biking adventures.

The bikes and gear: we were set up with Surley touring bikes, 2 rolltop drybag paneers, a nice waterproof magnetic front box (which i didn't realize i needed in my life, but fell in love with how easy it was to open and use while riding), straps, basic tools and repair stuff, chain lube, helmets, and basic lights.  The bikes had clearly been taken care of, and rode like it.  Drop handle bars, disc brakes, new chains (or at least very clean). Honestly riding these bikes made me realize i need a new bike, bc my old one isn't cutting it.  We went up and down mountains, through storms on country roads, fully loaded with camping gear and the bikes never let us down.

Service: Daisuke was our main contact, setting us up for everything we needed.  He was easy to communicate with (unfortunately our japanese is poor to non-existant), fluent in English, and just a generally laid back cool dude.  He kept our bags in storage for us (for a small fee),  and worked with us on drop off, as our timetables were not set in stone.  He actually ended up meeting us in Sopporo at our hotel to pick up the bikes and drop off our bags, which was hugely convienient and saved us another semi painful subway trip with all our gear.  

Really enjoyed working with him and Sparks, it made our logistic easy, which made it a really special trip.  Would certainly recommend Sparks and biking around the Hokido country side for anyone with an adventurous spirit looking to experience Japan on bike