Your universal is a 15 clone. The serial # is at the base of the pillar in your last photo, but honestly, it won't help you much. Records from the Japanese are sketchy to none. The arm to hold the motor on is substituted from Singer, but we don't see the motor to see if it is, also. Oil it up and enjoy it and it's birthday can be whatever you choose.
I got a kick out of your character on the back of your tablet.