I use Buyee to purchase things off of Mercari! I've always received items in great shape and very quickly. My only complaint is when you go to consolidate a package they charge 1,000 yen for it and that does not include packing it beyond its original packaging (you have to pay even more for that). I wish it would only cost money to repackage it, not to combine and ship the items as is because it just shows up in this thin bag packaging. Other services i've used haven't charged to consolidate and they actually pack it into an actual box over a thin material sleeve to send it on. That's the only downside I can think of though!