This is a story about Earth in the near future, a future where aliens have become commonplace in everyday life. And as soon as college student Shiori turned into an adult, she found out she was Sibyl’s, o...

Like a typical teenager, there is nothing Tsubaki Ryuuta wants more than to not stand out from the people around him. Unfortunately, on his way to school one day, he is run over by an alien. The alien prompt...

Thanks to deviant sexuality (lolicon, obsession with 2D girls, etc.), the human birth rate has declined, and humanity is headed for extinction. A cute loli girl from outer space, called Muumo, has come to ea...

It is the year 2199. The Gamilans, a hostile alien race, have bombarded the Earth, rendering it virtually uninhabitable and edging humanity to the verge of extinction. Mankind’s last, best hope for surviva...

2199 will be Earth's final year unless the voyage of the space battleship Yamato can succeed! The alien Gamilas have devastated the biosphere, determined to reshape our planet into their own new home. But a ...

The story, set in the United Kingdom in 1901, centers on a photographer. In the first chapter, the photographer is on his way to deliver a finished portrait to a client when he encounters a flying object fro...

"It was love at first sight." Taiga Hoshino is a regular guy who works at a delivery company, but when he gets kidnapped by aliens his life turns around completely! A fluffy, floating alien claims to have fa...

An alien, Mumu, who came to regain the technology lost by his race. The everyday life of an ordinary college student collapses because of his arrival...? A cat shakes the earth! Spectacular romance!!

The girl I fell in love with is an alien? I, the class president, happened to fall in love with my classmate, the eccentric Haru. I confessed my feelings, but her true identity was an extraterrestrial who ca...

"It's said that 95% of UFO sightings are shams, but...?"

Puruka is a parasitic alien who came to Earth in order to have offspring. After being saved by a busty high school girl named Fuuka, he begins to live inside of her head. It seems like he'll easily be able t...

The series' protagonist is Takashi Horimachi, a fifth grader at "Anytown" Elementary School. A transfer student named Taro Tanaka enters Takashi's class. Taro Tanaka turns out to be a space alien. Takashi be...

Grendizer follows the adventures of Duke Fleed, the prince of Planet Fleed, who, disguised as Daisuke, a farm worker, fights against the forces that destroyed his planet, the Vegan Empire, also the creators ...

UFO Robot Grendizer is the third entry in the Mazinger Trilogy by Go Nagai, following Mazinger Z and Great Mazinger. This particular incarnation was illustrated by Gosaku Ota and published in Boken Oh, Otomo...

The world is being assimilated by a crazy religion, and to stop it I have become their satan. The religion is controlled by aliens, and people don’t have a clue. The world says that aliens don’t exist, b...

Decades ago, a being known as the Giant of Light joined together with Shin Hayata of the Science Special Search Party to save Earth from an invasion of terrifying monsters called Kaiju. Now, many years later...

"[...] it's a very nice doujinshi about a busty light giant called Nana by Sasaki Maru." -- Kusanyagi

A side story of showa era Ultramen before they came to Earth for their respective series.