MikaHisu

MikaHisu is the femslash ship between Mikasa Ackerman and Historia Reiss from the Attack on Titan fandom.

Canon
Mikasa and Historia's relationship is very mixed throughout the series as at first Mikasa would threaten Historia that she wouldn't spare her life if she were to got in her way, as Ymir was helping Reiner and Bertolt since they kidnapped Eren and were trying to bring him back to Marley.

After this Mikasa and Historia's relationship is shown to be steady, Historia and Eren were once again kidnapped and were taken to the Reiss Chapel by Kenny Ackerman and his Anti-Personnel team where Rod Reiss planned on making Historia eating Eren, this of course fails as Historia throws the titan serum onto the ground. As Rod Reiss transforms into a titan by licking the thrown serum, Historia is flown away and Mikasa catches her on time. Afterwards, Historia becomes the true Queen of the walls. As she became Queen, Mikasa tells Historia to punch Levi which she does as she develops confidence and strength in herself.

In the time skip, it's revealed that Mikasa has political power as she's a decedent of the Shogun Clan, those who are decedent from the clan is part of the Azumabito Family. Historia is happy to find out and tells Mikasa that they can both share that they hold a heavy burden on their shoulders because of their birth, meaning Mikasa was the last Asian in the walls due the Shogan Clan working alongside with the Ackermans after they turned away from the Royal Government causing them near extinction, and Historia being rejected by her family as she wasn't suable to become Queen due to her father having an affair with her mother who was a servant. Mikasa blushes as Historia comments how she's glad to have her as her companion.

Fanon
Majority of shippers of this usually prefer this ship over their rivals, EreHisu and EreMika, which are very popular for both characters and would often cause commotion in the fandom with shipping wars.

Due to Historia being currently pregnant, some fans believe if the child were Eren's, Mikasa wouldn't care but the same time she'll feel heartbroken. But it's heavily hinted that Historia knows that Mikasa has feelings for Eren.