A younger version of Azur Lane's Belfast. Localized as Little Bel in the English version.
Created when Belfast walked in on an experiment being conducted by Akashi and Yuubari. Belchan says her name is Belfast. Belfast explains that as a shipgirl, she was born in her current form and was never younger or smaller. No one was able to explain exactly what Belchan is in-game.
This tag implicates belfast_(azur_lane) (learn more).