The Phantom of Night City Cyberpsycho Sighting may be extremely dangerous, but it is also worth it. There are two different Legendaries up for grabs from this singular event in the game, and one of them can be gotten without even fighting the Cyberpsycho.
You can find this Cyberpsycho Signing near the Halsey and MLK Fast Travel point in Corpo Plaza at the City Center. There will be an exclamation point just to the northeast of the marker.
When you get close, Regina will call you, warning you that there could be a Cyberpsycho in the area. If you are here very early in the game, you want to quickly duck inside and head to the right. Here you will find a container near the motorbikes, just along the wall. Look inside to find some Legendary Mantis Blades and then get out of dodge.
If you do want to fight Akuhara, you have a couple of tactics available to you. If you stay inside, Akuhara will attack you with a Katana. He is fast, and he hits like a truck, so you want to time your dodges well, unload on him with Shotguns, SMGs, and other up close and personal weapons. If you have suitable Quickhacks, you can weaken him before the fight. You do not want to get caught up in a melee battle with him, as he has vastly more health than you do unless you have a very late game build.
If you have a good Sniper Rifle, you can simply sit outside the small gate you use to enter the area and snipe him down. He will take cover behind a broken wall and fire back with a Smart Assault Rifle, so be prepared to hug cover and heal yourself.
This is another easily cheesed Cyberpsycho Sighting thanks to weak AI combined with an arena that you can easily take advantage of, so if you are struggling we would recommend just going with the ranged fight option and cheesing him.
After Ahukara is down, be sure to call Regina and check his body, for a Legendary Katana with extremely impressive stats.