Dorei-ku The Animation (2018, TNK / Zero-G)

A retainer-like device known as the "SCM" is being sold on the internet and rumours have it if you wear it and challenge another person that's also wearing to a duel, you can turn them into your slave when you win. Ohta Yuuga comes across Eia Arakawa one day after dumping her best friend. After discovering how daring and smart she is...