Zombie

Zombies are main antagonists of the series.

Cause
When Akira’s Party visited the lab Tsuru is working in they theorize it was likely the result of genetic and bio engineering for the military that cause a virus here

Infection
The Virus can be spread if a zombified individual bites a living being or if they consume flesh of a zombified being. Once it happens it takes some minutes to hours to happen varying on the person with Shizuka taking longer to get infected than most.

Physiology
When infected their veins are exposed with heir eyes exposed here. Sometimes mutations can happen like the Chairman getting larger or Zombified Shark spourting out human legs it ate from earlier to walk on land.

However Zombifies can’t actually see well and mostly rely on sound as they attracted to loud sounds which can be dangerous for those who panic easily.

Protection and curing
If someone wears protection that stops biting they won’t be infected like Akira’s superhero suit made from a shark divingsuit though it will still hurt from the pressure. Izuna has complete immunity to Zombie Virus as her immune system will destroy the zombie virus here.

So far while there is no way to turn a zombie back to normal so far. there were some serum made such as one used for Shizuka when she got biten by a zombie using Izuna’s blood who has immunity to it that stopped the virus from infecting her with