Guys that rifle doesn't look like a trainer to me. The receiver shape looks like a Type 99 Naval Special rifle which uses a cast iron receiver and a bolt that locks into a barrel extension. If you look at the photo of the breech area you can see the barrel extension sticking out of the receiver ring. Do some searching on google and gunboards.com for Naval Special Type 99's and you will find photos of rifles like yours. These are extremely rare and have very low production numbers. I recommend not attempting any cleaning or restoration until you have some more information on what you have.