If you've read manga for a decent enough amount of time you more than likely have noticed that some mangaka have a habit of re-using certain character design "templates", if you will, and while some may try writing it off as "laziness" the truth of the matter is that there's actually a name for this concept: The Tezuka Star System. Officially titled the Tezuka Manga no Character Ichiran/Tezuka Manga Character List in Japan, the Tezuka Star System was the late Osamu Tezuka's habit of reusing certain characters across his various manga, as though they were actors being cast in multiple roles across numerous productions, with the English name for this concept being a reference to the real world "star system" that Hollywood utilized from the 1920s through the 1960s. For example, iconic characters like Astro/Atom, Black Jack, & Don Dracula have made appearances more or less as themselves (or, at least characters with the same designs & names) across various manga or anime from Tezuka, while characters like Rock Holmes, Ham Egg, Shunsaku Ban, Acetylene Lamp, & many others appear in various productions as essentially the same character they play in other ones. Therefore, Rock is often a "bad boy", Ham Egg is a villain, Shunsaku is a well-meaning good guy, Lamp is conniving, etc., & even Tezuka himself was a part of this, appearing in various series as a mangaka. Tezuka liked to treat his characters as though they were actors, even joking that some received "pay raises" if they performed well, and by reusing these characters readers could instantly get a bead on the kind of character these "actors" were portraying in a work, and sometimes he could even have them "play against type", like how Rock was originally a consistently heroic character before going "bad".
One mangaka that absolutely adheres to the Tezuka Star System is Masami Kurumada.
As you can see in the image above, for his 50th Anniversary art exhibition that was unfortunately cancelled, Masami Kurumada tends to use the same character template for his main characters, with some exceptions, like Okita Souji in Akane-Iro no Kaze, Maya in Evil Crusher Maya, and most notably Rei Kojinyama in Sukeban Arashi, which remains Kurumada's sole female lead. In fact, it's with Kurumada's debut work from 1974 that his form of the Tezuka Star System really got started, as Rei would be "recast" as Kiku Takane in Ring ni Kakero, her love interest Morita would be "recast" as Jun Kenzaki in RnK, & even her rival Shizuka Ayakoji would eventually "return" as Himeko Hojo in Fuma no Kojirou, among some other "recurring actors". Of course, the big one would be Ryuji Takane from Ring ni Kakero, who would become the recurring main character template I previously mentioned, being "recast" for Kojirou in FnK, Jingi Kikukawa in Otoko Zaka, Pegasus Seiya in Saint Seiya, Aoi Tendo in Aoi Tori no Shinwa, Sho in Silent Knight Sho, Teppei Takamiya in B't X, & most recently Pegasus Tenma in Saint Seiya: Next Dimension; it's really no different than how Tim Burton would often cast Johnny Depp or Helena Bonham Carter in many of his films (8 & 7 out of 20, so far, respectively). However, when it came to one specific work, Kurumada seemingly decided to take the Tezuka Star System to its absolute limit.
Upon debuting Saint Seiya in Weekly Shonen Jump Combined Issue #1-2 of 1986 Kurumada had been making manga professionally for nearly 12 whole years, and while there were naturally long-term Jump readers who would continue to read the magazine for as long as they could, there was also now new, younger, generations of readers who might have at least heard of Ring ni Kakero or Fuma no Kojirou, but had only really known of Kurumada by way of Otoko Zaka's failure, at best. Therefore, Kurumada seemingly decided to reutilize many concepts, names, & terminology from his prior two hit works, but mainly from Ring ni Kakero, and repurpose them into new forms, if possible. That way, long-term fans of Kurumada's work would be able to identify the reference & have some bonus fun in that way, while the newer readers would be able to experience it for the very first time, and ideally in a way that's unique for them. In essence, Kurumada took the Tezuka Star System when it came to Saint Seiya & expanded it into more than just characters, and while some might try to argue that it's, once again, "laziness" there's no denying that the concept worked, as Saint Seiya is what people immediately think of first, despite some of its stuff being callbacks to Kurumada's prior works.
While I can't claim that I've collected them all, let's take a look at the ones I picked up on while re-reading Saint Seiya for the recent review of the manga I did.