Shipping luggage to another city in Taiwan?

I’m currently traveling around Taiwan after a couple of months in Southeast Asia. I’d like to rent a bicycle for a few days and travel up the east coast, however I have too much baggage. So I’d like to ship my big backpack probably from Taitung to Hualien, and then pick it up a few days later.

I’ve heard there’s a system here that’s similar to the Japanese takkyuubin service, where you can go to a convenience store, fill out a form, and they’ll ship it to another convenience store (or a home address) for you to get later. Does anyone know how it works in Taiwan? Would I be able to take it to e.g. 7-Eleven in Taitung, and then pick it up 3 or 4 days later at another one in Hualien? And if so, any idea around how much that would cost (15-20kg)?

Thanks for any advice

yes.