Learning Kirai at the moment for our local slow grow and I think the core takes are Ikiryo (obviously), Datsue Ba, at least 1 Onryo and 1-2 Seishin. Whisper on Kirai is a must take too imo. Then from there, simply flavour to taste (1 or 2 Drowned, Goryo, Shikome, 3rd Seishin etc etc)