Sending parcels from Japan

Okay, I'm in Tokyo on vacation and I've gone slightly crazy buying stuff. I'll need to send some of it home as it won't fit in the suitcase - not heavy, but bulky. Figures and such.

Where's a good place to buy packaging and cushioning for the parcel? I'm near shinjuku, so if anyone knows a good place in the area, or any good ways to deal with packing and shipping them off that'd be ideal.

Thanks for your time, all!

You should be able to buy everything you need at the post office. Surface nail takes a few months but it's affordable.