We all don’t know yet
It's not memory loss but worse - a brainwash. When he was in the hospital, someone (I don't remember) from the enemy side found him and kidnap him. The next time that he met Asami (after the brainwash) , he pretended that he's glad that they met again and he missed Asami, etc. But while they're making love Akihito planned to use a knife to kill Asami, but of course Asami found out, they have a little fight, then Akihito escaped and enter an unknown black car.
We don’t know if it was brainwashing.
If he lost his memory and was simply fed lies (probably with the help of a certain photograph of him giving a blowjob to Sakazaki), that’s not brainwashing per se.
Omg what happened to Akihito? Oh no i hope it's not a memory loss or something! Can someone tell me...