To clear up a few things:

1. Garuda has an interline agreement with JL, but this is only relevant on a single ticket. Whilst it is possible for GA to through-check onto JL, there is no reason they have to do so.

2. I have no idea whether the bribe will work, it may be that the agent is not empowered to check through.

3. If they don't check through you will have to collect your bag in NRT and then check it in again with JL, respecting the cut-off time to do so. You will then need to go through security again. With your timing this is getting tight.

4. If your flight into NRT is late or cancelled, your JL ticket will auto-cancel; you have no protection and are fully on your own to get to ORD. This could be expensive.

Just a few things to consider.