I do not like this game the author of this game very much in an ethical sense.
The author may say that the main female characters are his own original characters, but that is an outright lie. The pictures of the main female characters were originally created by a completely different person who used the pictures of characters from a pay-to-play game without permission.
Perhaps thinking it was bad form to use it as it was without permission, the author drew his own picture based on it, but... The pictures have deteriorated in terms of quality, the essential character designs have remained virtually unchanged, and I must say that there is a lack of awareness of copyright.