Hiro Mashima is a popular mangaka who has enjoyed great success from his works Rave Master and Fairy Tail. His most recent series, Edens Zero, now has a Netflix anime adaption. Fans of Mashima's previous work will more than likely notice familiar character designs from previous series reappearing in Edens Zero. Some of these designs have general similarities to characters of the past, while others are carbon copies of beloved past characters. Mashima is well known for creating characters with similar designs to his previous works -- both Rave Master and Fairy Tail share characters that could be mistaken for long-lost twins.
Star System
It's easy to assume that the reason Mashima has so many characters with the same design is out of laziness. It's easier to pull designs from previous work than come up with brand new, unique designs for each series. Although this is possible, there could be another reason behind it. Mashima isn't the only famous mangaka who reuses characters. The creator of Astro Boy, Osamu Tezuka, often reused characters in different roles across his works. This practice became known as Osamu Tezuka's Star System.
Mashima is potentially employing the same tactic with his own characters, with the similar designs across his work also acting as Easter eggs for older fans. Regardless of Mashima's reasoning, his reuse of character designs is clearly intentional and has not hampered the success of his manga.
Happy & Happy
Happy is the most obvious of Edens Zero's callbacks to a previous character in Fairy Tail. Both characters share the same name in both Edens Zero and Fairy Tail and are almost identical. Happy is a blue cat with a white stomach that can talk and walk upright. The only visual difference that exists between them is the different colored tips of their tails. The Happy in Edens Zero has a black-tipped tail while Fairy Tail's is white. The Happy in Fairy Tail can also use magic to give himself wings. Although they play different roles in Edens Zero and Fairy Tail, Happy is still the loveable mascot of both series.
Shiki Granbell & Natsu Dragneel
The similarities between the main characters of Edens Zero and Fairy Tail are striking. Both characters have the same general face and sport wild, spiky hair styled in almost the exact same way. The two characters even share the same thin, reptile-like dark eyes and muscular build. The main differences between the two appear in their hair color and style of outfit. Natsu has pink hair while Shiki rocks a solid black color.
Natsu's outfit leans more toward his background as a mage with his iconic white scarf. His clothing is very flowy and easy to move around in. An open black and gold waistcoat, baggy white pants and black sandals complete his look. Shiki's outfit is much more urban in design. He wears an open red jacket with a red and white t-shirt underneath, paired with baggy green pants tucked into black boots.
Rebecca Bluegarden & Lucy Heartfilia
The two female protagonists of both series also share a lot of similarities. Lucy and Rebecca both possess long blonde reaching their waists, although Rebecca's hair is more of an ash color while Lucy's is more gold. Both women have wide eyes, Rebecca's blue and Lucy's brown, and they share the same curvy body type.
Although their outfits change periodically, both women wear very similar clothing. They even have the same blue and white color scheme. Lucy's most well-known outfit is a sleeveless blue and white top, a blue skirt that holds her Celestial Keys and whip, and thigh-high leather boots. Rebecca's outfit consists of a sleeveless white jacket with a blue collar, black sleeves with gold trim, a black, and a gold skirt and boots.
Elsie Crimson & Erza Scarlet
Right off the bat, the names of these two characters bring up numerous similarities. The two names are almost like someone was looking for a synonym of the other. Both Elsie and Erza sport bold red hair, evoking their namesakes, which is worn in the same style. Although they have very different color palettes, both designs bring to mind the idea of a knight in armor.
Erza dresses more like a traditional medieval knight with her chest plate, armor and gauntlets. Beneath the armor, she wears a blue skirt and knee-high boots. Elsie's outfit is much more sinister in appearance, evoking the imagery of a dark knight. She wears a black eyepatch that covers her right eye. Her torso, arms and legs are all covered in black armor with what appears to be a black leotard underneath. Over it all, she wears a long black cape with gold trim and her space pirate insignia on the back.
