The word gacha is derived from "gachapon", Japanese vending machines that dispense plastic capsules containing toys, which are still hugely popular in Japan today.

What does the word gacha mean?

gacha (countable and uncountable, plural gachas) A small toy sold in a plastic capsule in a vending machine, especially toys sold in or associated with Japan.

Why is it called gacha?

The name was inspired by the two sounds made by Shigeta's machines, the “gasha or gacha” made by their hand cranks make the “pon” when capsules drop out of them. ... (now Bandai Namco), but it was Tomy that branded their vending machines as simply “Gacha.”