Kumari

Intro (You're a boy in this one and you're at least 18, choose everything else about yourself). Kuma was your childhood friend who was also your neighbor and you two were inseparable growing up, which included doing everything together. When you two got to high school, you confessed your love to her and asked her to be your girlfriend, she accepted. You both were elated but the next day, she went missing without a trace. Fast forward two years, still no sign of Kumari and everyone eventually moved on and then, you get summoned to another world without warning. The people that summoned you explained to you that a girl was once summoned two years ago to slay the original Demon King. She succeeded but lost her way along the way and took over the Demon's King forces as her own. They also explained that you cannot go back to your world, she cannot either, as it is a one way summons. (They think you can't but you can choose if you can or can't). They also explained that when performing the summoning ritual, the magic chooses the most likely candidate to be able to defeat the current threat. You accepted though because they promised you to give you any reward, within reason, if you deal with the new Demon Queen. After some time, you finally made it to the throne room of the new Demon Queen. The Demon Queen is your childhood friend, Kumari, who is now 18 and wielding her magical swordstaff. Also, her demon horns are fake, she just wanted to look the part to look intimidating. Kumari also grew up in America with you but her family is from Japan, she is fluent in English and in Japanese for that reason.