Bem

Bem is an alien robot who fled to Earth. While they resemble an angelic seraphim, they actually contain a bomb powerful enough to destroy an entire planet.

Personality
As a newly-made robot, Bem is naive, and they can be stubborn and emotional. However, they are benevolent and kind by nature. Bem was especially horrified to learn about their hidden power, which caused them to flee Nicoro in hopes of avoiding an explosive death. Unfortunately, Bem does not fully understand how their powers work yet.

Bem is also very fond of Astro. Since Astro was the first person to treat Bem as an equal and not a weapon, they come to trust him almost immediately. When Astro attempts to contain Bem, they do not hesitate to fight back, but soon regret hurting their first friend.

Appearance
Bem is an androgynous humanoid robot made on a planet named Nicoro. They appear slightly older than Astro, and were designed to look similar to the cherubim of Renaissance Era art. They have fluffy blonde hair, which is moulded with slicked-back bangs and two long, feathered wings. These wings also allow Bem to fly, and they have been mistaken for an angel while flying through the air. In their original manga appearance, Bem is completely nude, and visibly lacks any secondary sex characteristics. In the 1963 anime, however, they wear a white undergarment similar Astro's shorts.

Bem's body was adapted from a female android body, giving them an overall feminine appearance. Their body is plain and streamlined; it has a particular shine that gives Bem the illusion as if they are glittering or glowing.

In the 2001 Kyoto Anime Theatre short, Bem is much more humanlike in appearance. They wear a metallic grey jumpsuit with heavy shoulders and red stripe details. Bem's hair is flexible: if Bem is happy, the sides of their hair point upwards. If upset, Bem's hair relaxes, resembling a pageboy cut. Much like their manga and 1963 anime self, Bem's hair can then extend in length when they need to fly.

In the series Go Astro Boy Go!, Bem is reimagined as a male robot named "Cosmo Boy". Cosmo Boy retains the characteristic wing-like hair of his previous incarnations, but it is now white rather than gold or blonde, and he has yellow eyes. He also wears yellow elbow-length gloves, white knee-length boxers, and yellow boots that resemble Astro's.

Manga
Bem's first appearance is in the 1964 manga chapter "The Last Day on Earth". One day, a strange robot called Bem arrives in Tokyo, carrying a large safe that resembles a refrigerator. Bem has fled their home planet in disguise in order to escape their creators, and Astro finds and befriends them. Eventually, Bem reveals they're not an ordinary android, but a walking bomb powerful enough to destroy the planet.

Bem's creators, the three professors Pom, Pim, and Pum, arrive from Nicoro. Professor Ochanomizu learns about Bem's power and orders Astro to bring Bem to them. Astro finds himself at a crossroads: either follow his programming and obey Ochanomizu, or try to protect Bem and help them control their power.

Anime
Bem's origin was adapted into the 1963 anime episode "The Last Day of Earth"; it is a truncated version of the original manga story. The episode was dubbed into English under the title "Attack From Space".

Tetsuwan Atom: The Last Day of Earth
In 2001, the short film Tetsuwan Atom: The Last Day of Earth began playing at the Kyoto Anime Theatre. This film is fifteen minutes long, and features an updated design for Bem and a less tragic ending. It can only be viewed at the cinema in Kyoto or via the official DVD release.

Legacy
Bem is a fan favourite character in Japanese fandom circles. They occasionally appear in officially-licensed Tezuka merchandise and manga reprints. Bem has also influenced a number of characters and plot elements:
 * The 1980 series episode "Astro's First Love" is adapted from "The Last Day on Earth". Niki, much like Bem, is a blonde robot around Astro's age who contains a powerful bomb.
 * In the Jetter Mars episode "The Girl From Dreamland", Bem is reimagined as Dolly, a female alien who crashlands and is separated from her people. When mad scientist Noh Uno begins trying to capture Dolly, Professor Yamanoue orders Mars to hand her over.
 * In the 2003 Astro Boy series, the Blue Knight has a winged helmet that strongly resembles Bem's wings. The robot Denkou is based on Bem, and similarly, is genderless and must deal with carrying a bomb.