Fumetsu no Anata e Season 2 - Episode 11 discussion : r/anime
Strengthening Prince Bon's character from an "obnoxious" figure to a pragmatic and surprisingly strong leader.
These three warriors are not currently immortal, but Bon recognizes their potential to aid Fushi and wants him to develop a "reserve" of personas in case the Nokkers steal his existing ones.
Effectively "table-setting" for the Renril Arc, building momentum through interpersonal friction rather than just action.
