Do you think Akira Nishikiyama and Prince Hans would make a great partnership together and join forces because they are one of the most evil villains and have many similarities like:
They want to make sacrifices and fight for their love intrest. Execpt that Prince Hans wants to kill both the sisters while Nishikiyama wants to claim Yumi for himself from Kiryu
They had a tragic past. Hans was abused by his family according to the novel A Frozen Heart and Nishikiyama's family mistreated him, the patriaches shamed him and he lost his sister.
There is one difference. Hans is the twist villain in Frozen while Nishikiyama changed from a deurtagonist to an antagonist in Yakuza/Yakuza Kiwami.