This would be an indication that there is a load, which would explain your drain. I don't think there should be a spark if everything's off - unless your bike is fitted with an alarm or other third-party electrical stuff.
If you're not leaving your key turned on, then it sounds like there is something wrong somewhere in your wiring, so that power is being drained all the time.
Having said that, the problem could very well be a short between two wires that should otherwise be isolated. It could also be a faulty component, such as the key switch or a relay, or a faulty connector - for example water in a connector could make an unwanted connection.
Do you know if there's any 'added' wiring on your bike? Any additional switches or accessories that are non-standard?
Usually, most wiring problem can be traced to three principal reasons:
1 - corrosion. Rust kills connections, and a rusted connector can make a short.
2 - heat. Engine or exhaust heat can easily melt a wire's insulation if it's badly routed or not secured.
3 - mechanical friction. On bikes especially, the bit of wiring harness most at risk is around the steering column. That's because every time you turn your handlebars, the harness flexes. If it's badly routed, wear will be accelerated and failure will follow. Any bit of wiring that moves regularly is at risk.
The first thing I would give it is a thorough visual inspection. You'll be amazed at what you can find if you really look properly. This involves a decent flash light and probably the removal of a few components - like the faux-tank, intake cowls, side covers, seat etc.
If you can't see anything obvious, then I would try removing the fuses one by one and attaching/removing the charger to the battery (fully connected) to see if the spark is still there. This could help you determine which circuit the fault's in.
After that it's down to getting the electrical schematics from the manual and a multimeter..