it's a kind of isekai, 3 kids get spirited away (from japan) to another land that has a rly geometric shape. there's 12 (possibly 13 but unlikely) kindgoms in this land. Protag girl has weird colored hair (red?) and it's a plot point about how she hated japan because of bullying/ridicule or summin she got. Only she (of the 3 kids) can understand the language in this new land. She's actually turns out to be destined to be ruler of one these 12 kingdoms... (and originally from this land) the one which she is destined to rule has been taken over by some woman associated with the last ruler there and has taken the mystical being (a keiren?) that says who the legit ruler is hostage/sedated? summin like that.
Been a long time, watched the animu ages ago. Wanted to read the manga (assumin it's not ova as in ends in a weird spot without a real end).
Cheers for any help.