Kotaro is a mysterious individual who won't tell anyone his past and Xerxes promises the group that it isn't anything they need to know about and it's something Kotaro will need to give out on his own time. Kotaro is probably the guy least likely to recruit a new member so you're person would probably have to have had to show him how well she fights especially for one as carefree as her as Kotaro is one of those 'lone ranger' types figuratively and literally.