It was bought (if I remember correctly) on November 26, 2021 at 2nd Street in Tsukuba, Japan for around 10 bucks. 2nd Street is a Japanese second-hand clothing chain and there is one of their stores around 500 meters from my parents' house in Tsukuba. Since I visited Japan in 2021, this store became my favorite (I also visited other 2nd Street stores, but the ones especially in the center such as Tokyo and Kyoto are not as appealing as the one in Tsukuba).
The sweater is from Coen, a Japanese apparel brand. This is my favorite sweater so far. I've been wearing it in Japan, Germany, Colombia, and many other places. It can be paired with any trousers or even without trousers.
When I visited Tallinn in 2023, Pia described the color as "burning blue".