Eriko is Ryūji's 19 year old second cousin. She really likes her cousin and despite the fact that she has been studying in America for some time, she returns to Japan to see his face and also to intercept a Lost Precious that FANG took from her ten years ago. Despite the risk of taking anything that FANG believes is theirs, she doesn't back down because she believes the contents, which she suspects to be an S rank Lost Precious, will prove her worth to the other Lost Precious hunters.