Although Kirara has quite high damage with her Ultimate, it is best to focus on maximizing her shield so that she can protect us from all the damage we receive. If we build her well, we may be able to do without a Healer, but it is true that in that case, it will be very useful to have a character like Xingchiu who can provide us with damage reduction and a slight healing (better to have some healing than none at all).