Gibiate

Tokyo, 2030. A pandemic called Gibiate, which transforms all regardless of age, sex, or race into monsters known as Gibier, has spread throughout the world. This is the age that the samurai, Kanzaki Sensui, and the shinobi, Sanad Kenroku, find themselves in after traveling through time from the Edo era to meet the Doctor and his assistant, Funada Kathleen. What future lies in store for Sensui and Kenroku as they face these monsters for the first time?

After meeting Kathleen, Sensui and Kenroku are invited into the camp where people have been living together. Kathleen challenges Sensui to a duel, hoping to learn how strong he is. Shortly afterward, the camp's lights suddenly go dark and the Gibier attack. Can Sensui and Kenroku fight against these unknown Gibier?

Sensui and the others decide to set out for a new location. Along the way they encounter a type of Gibier they have never faced before. Yet during that challenge a third man who has traveled through time like Sensui and Kenroku appears before them!

With aid from Onikura Yukinojyo, a warrior monk who traveled through time, Sensui and the others manage to repel the powerful Gibier, Meteora, and then stop in at a nearby shopping mall. There Sensui and Kenroku's past is revealed, as well as how they first met one another. Yet as their group sets out for the new destination, a new peril approaches!

Sensui, Kenroku, Yukinojyo, and Adam manage to escape after being attacked by a huge horde of Gibier. They decided to take a break while on the move, only to be attacked by five men calling themselves the Galients! Do they have fight other humans now on top of the Gibier?! Source: crunchyroll

A lone woman appears when Kathleen is in danger. Is she an ally or an enemy?! Will they be able to escape from the desperate situation within the tunnel? Sensui's past is finally revealed, along with his history with his Master and the origin of his dual wielding style...

Ayame joins their group, but they continue their journey toward Niigata, they once again encounter Meteora! How will Sensui, Kenroku, and Yukinojyo overcome this danger as they struggle against Meteora's fierce assault?!

When the group makes a pit stop to try and allow a wounded Sensui to rest, Yurika is stabbed by Gibier. Yet even as Yurika's injury brings great sadness to them all, a swarm of Gibier attacks without mercy... Can they make it through this disaster?!

Sensui is wounded and unable to move, so Yukinojyo takes a stand all alone to protect him and Kathleen from the Gibier... After finally overcoming countless hardships, the group arrives at their final destination where a large horde of Gibier lies in wait!

A huge horde of Gibier awaits them at the research center, so Sensui and the others steel themselves for battle. Doctor Yoshinaga continues his research, but can he complete his vaccine?!

Their group spends an enjoyable night with their new allies, the Galients, but then they're attacked by Meteora... Doctor Yoshinaga continues his research toward a vaccine in the research center, and his past is revealed to all...

With the memories of their dead comrades behind them, Sensui and Kenroku put up a fierce fight to the death against the transformed Dr. Yoshinaga. All is revealed and the story reaches its shocking conclusion...