Both stories consist of powerful women with unimaginable power now sealed with it only being able to be lifted through discovering love (or kissing). Their male partners both have considerable skills or potential. However in both stories, once their powers become unsealed, their loved ones are snatched away and somehow goes to the enemy's side and now they must fight to return them to their original state. Both stories are filled with action, suspense, and romance.
Similarity : MC in journey to find/rebuild they comrade/team
+ Onepiece >> luffy must find atleast 12 peoples to created straw hat pirates group
+ The Legend of Maian >> Felicia in journey to find 13 regis knight (her loyal servant)
Shuria looks like Metaricana, Felicia is awakened by a virgin too (Felix,LOL) the difference is that Felicia always needs a kiss to release her powers.There a lot of hot witches and such in both, and they're no way weaker than males, speaking of power both worlds are overpowered with walking Nukes in Maian and at a FREAKING COSMIC level at latter volumes of Bastard!! And magic works very similar on both too.
At first I was left perplexed: how could Dal Young have been 'inspired' to create Maian when Maoyuu Maou Yuusha seemingly came to be a good few years after Maian began?... Then, I remembered that Superior and Maoyuu have practically identical premises.
Maian, Superior and Maoyuu share one vital element that makes them the series they are: a hero (descendant in Maian) finds himself traversing the world with an 'evil', world-conquering, voluptuous woman. As they travel together, it *SHOCKINGLY* turns out that Ms. Evil is actually a good person, and romance blossoms.