Ad always carry an allen wrench of that size with you when you ride. If you need access to the battery when out riding, you are screwed without it.
On this bike the seat and tank are secured with 12mm hex head bolts.
At an absolute minimum, always carry a 7, 8, 10, and 12mm combination wrenches, a P-2 phillips and 3/16" flatblade screwdriver and medium size pliers with you. (throw out the chinese reject junk that comes with the bike and use real tools) That won't fix all the problems however it'll go a long way in limping home while doing city and populated area riding.