Tsutomu Senkawa is an average high school kid who is busy studying for his senior entrance exams. One day, Tsutomu stumbles into a man who is on the run from Space Federation Officer Birdy Cephon Altera. The man throws Tsutomu at Birdy, who kills him only to realize her blunder right after. In order to save his life, Birdy and Tsutomu's body merge into one, and they must switch back and forth between being a high school student and being a Federation officer on the hunt for interplanetary criminals.

In the near future, large mechs called Labors are made to assist in various reconstruction projects in major countries around the world that are being threatened by global warming. In Japan, the government has enacted Project Babylon in order to conduct land reclamation. Labors are also being pressed into police and military service aside from civilian use.

However, terrorists are now attempting to use labors to make themselves heard, as well as common criminals, thugs and guerrillas. The National Police Agency established the Special Vehicles Division, an all-labor task force to combat the potential use of labors for criminal/terrorist activities.

The manga received the 36th Shogakukan Manga Award for shōnen in 1991.

Kuze Shunpei, a high school student, is on spring break going to Hokkaidou when he loses his wallet. Stranded in the mountains with no money and his motorcycle having run out of gas, he passes out in the snow on the side of the road. When he wakes up he finds that he's been saved and brought to the Watarai farm, a horse ranch that breeds race horses. There he meets a host of various people, ranging from stable hands to the owner and his family (which includes four daughters).
Shunpei is completely unsuited for the farm life, and his city upbringing contrasts sharply with the hard labor required to help the farm out. Yet despite all this, he tries his best to become accepted. However, he constantly gets into arguments with Hibiki (the second daughter), who views him as useless. Things come to a head when Shunpei scares one of the horses, who throws Hibiki (Hibiki is a rider). Ashamed, Shunpei flees back to Tokyo for the rest of the spring break. But back in Tokyo, Shunpei begins to long for the simple farm life. Will Shunpei ever be able to return and prove himself to be worthy of being a member of the farm?
(Source: MU)

After two years of being dormant inside Tsutomu Senkawa, an accidental encounter with their old nemesis violently wakes Birdy up. With Birdy kicking evil's ass once again, the dark secrets of the experiments conducted by the "Agni" corporation are slowly revealed. They seem to be dabbling with human body enhancement, creating what they call "beast men," to combat the alien invasions related to Birdy.
(Source: MangaHelpers)

The Camera Club of Harukaze High School prepares to go on its annual photography trip. This trip was scheduled by Tosaka, an alumnus of the Camera Club. Through a travel agency, he was able to plan a "Stamp Rally" tour. This agency, however, is owned by Saionji Marii's family, and she despises the Camera Club.
(Source: MangaHelpers)

This is the remake version of Tetsuwan Birdy.

"The original manga ran in what is now Monthly Sunday, but when Masami Yuki began serializing Kyūkyoku Chōjin R in the pages of Shonen Sunday it began appearing infrequently, and was eventually abandoned. Only one volume was ever collected. In 2003 Masami Yuki moved from Shonen Sunday to Weekly Young Sunday, a seinen magazine, and began drawing a remake version, starting the story from the beginning." --Wikipedia