Monacoin is a very old altcoin (according their website has been created in Japan in 2014). I remember the name because "mona" is like an offense in north-east Italy

Ok geography apart, these have been minted by https://sakamt.co.jp/ SAKAMOTO Co., Ltd .
This design and other similar seems still available in https://store.medals.tokyo/items/41949494 they call this as "medals" and not coin.
they are selling also with other coins (made in pure silver)... thanks for sharing, their products are somewhat inspiring