Headcanon
Doing that headcanon meme: A lot of this is tentative and may potentially change as I get castmates and work through things with them. (A Shuki would probably require the most potential changes)
* Zaoumaru (Zanki's human name) was saved from a Makamou when he was in late middle-school, probably about Asumu's age, and knew then he wanted to be an Oni.
* He probably would have become a police officer otherwise--this is partly what attracted him to Todoroki
* It was the previous Zanki who saved him and Zaoumaru followed Zanki around for a while like a puppy before asking to be made his disciple. But after discussing it they decided on patience and that Zaoumaru should finish high-school before starting his training because education is valuable. Zanki did start teaching Zaoumaru guitar at that time, however.
* Because he wasn't continuing to college Zaoumaru wanted to start his training in the spring of his third year... but Zanki was killed by a Makamou. Zanki did leave his instrument (Retsurai) and Onjou (and his name) to Zaoumaru for the right time and Shuki agreed to take him as a disciple. He was 17.
* Shuki had trained many Oni, being an expert in spells and other older methods as she was, but Zaoumaru was her first full disciple. She was a very hard master and frequently a dick to Zaoumaru, especially in the beginning.
* Zaoumaru still developed a very strong devotion to her and put her on a pedestal... when he wasn't comparing her to Zanki. He was also strongly attracted to her, until she broke him of it and probably in an unpleasant way.
* they rubbed each other's sharp edges down, slowly developing a very strong bond, and Zaoumaru learned quickly and well and probably could have graduated before turning 20. But even though he agreed to take the name Zanki he didn't leave her to set out on his own. He started learning spells from her and only didn't learn one or two. He also learned how to play/fight with several other string instruments, including the harp.
* Retsuzan is a product of the learning of spellcraft. He didn't physically craft the guitar but he put the necessary spells and such on it so it could function. Because it is wholly his it wasn't passed down to Todoroki when he graduated the way Retsurai was. Also the reason he had access to a second weapon to begin with. not that the writers bothered to think of this. stupid writers
* He was 22 when Shuki tried to kill him and about to graduate. He spent months in the hospital and had to retrain himself after recovering to manage transformation again. He was sent to assist other Oni to help him get back on his feet (but mostly to make sure he hadn't picked up any of Shuki's bad ideologies). Sabaki was one and so was Hibiki (he learned taiko then) and he formed strong bonds with both. His heart has always panged a little ever since but usually not enough to cause problems.
* He'd dated in high-school and during his training (mostly because of his very good looks because lol he fails at pickup lines) but pretty much swore off women not involved with Oni after Shuki tried to kill him. His type is strong, powerful women (while he's not adverse to men he is far more attracted to women) so he had a brief affair with a female Oni but they lived too far apart to really date. He also dated Midori once or twice but it never became sexual. They got into involved discussions about weapons, spells and techniques instead.
* He's had a sporadic but long-term affair with an unnamed male Oni who he only sees in person maybe once a year at New Years. This is the only man he's ever thought to have a relationship with, though he's had the stray attraction or two (and maybe an alcohol aided makeout session or two as well). Friends with benefits, and mostly as a way to deal with lifelong bachelorhood for both of them. He was too content with it to actively pursue a relationship but won't say no to the chance, especially now with all the strong, attractive women in Camp.
* He was on his own again by 23 and worked very well and hard and then somehow met Todoroki (then Todayama) (possibly saved him) at around 30 and agreed to be his master quickly.
* His own experiences made him try to be as different of a master from Shuki as possible. As a result he tended to be entirely too permissive, especially at first. He got better as he got used to Todoroki's needs.
* He discovered a great love of teaching while training Todoroki and those two years were his favorite of his career.
* He would have kept Todoroki in training for another year or more if not for his injury (the knee was the primary cause but his heart was causing problems as well) forcing him to retire. He's come to understand that this was a good thing in Todoroki's case.
* He wanted to teach Todoroki spells but Todoroki had little talent
* he prefers not to use spells often as it is easier to rely on Disk Animals and his own abilities. But he does place great value on knowing them as part of Oni heritage.
... I think that's it. Possibly more to come.
* Zaoumaru (Zanki's human name) was saved from a Makamou when he was in late middle-school, probably about Asumu's age, and knew then he wanted to be an Oni.
* He probably would have become a police officer otherwise--this is partly what attracted him to Todoroki
* It was the previous Zanki who saved him and Zaoumaru followed Zanki around for a while like a puppy before asking to be made his disciple. But after discussing it they decided on patience and that Zaoumaru should finish high-school before starting his training because education is valuable. Zanki did start teaching Zaoumaru guitar at that time, however.
* Because he wasn't continuing to college Zaoumaru wanted to start his training in the spring of his third year... but Zanki was killed by a Makamou. Zanki did leave his instrument (Retsurai) and Onjou (and his name) to Zaoumaru for the right time and Shuki agreed to take him as a disciple. He was 17.
* Shuki had trained many Oni, being an expert in spells and other older methods as she was, but Zaoumaru was her first full disciple. She was a very hard master and frequently a dick to Zaoumaru, especially in the beginning.
* Zaoumaru still developed a very strong devotion to her and put her on a pedestal... when he wasn't comparing her to Zanki. He was also strongly attracted to her, until she broke him of it and probably in an unpleasant way.
* they rubbed each other's sharp edges down, slowly developing a very strong bond, and Zaoumaru learned quickly and well and probably could have graduated before turning 20. But even though he agreed to take the name Zanki he didn't leave her to set out on his own. He started learning spells from her and only didn't learn one or two. He also learned how to play/fight with several other string instruments, including the harp.
* Retsuzan is a product of the learning of spellcraft. He didn't physically craft the guitar but he put the necessary spells and such on it so it could function. Because it is wholly his it wasn't passed down to Todoroki when he graduated the way Retsurai was. Also the reason he had access to a second weapon to begin with. not that the writers bothered to think of this. stupid writers
* He was 22 when Shuki tried to kill him and about to graduate. He spent months in the hospital and had to retrain himself after recovering to manage transformation again. He was sent to assist other Oni to help him get back on his feet (but mostly to make sure he hadn't picked up any of Shuki's bad ideologies). Sabaki was one and so was Hibiki (he learned taiko then) and he formed strong bonds with both. His heart has always panged a little ever since but usually not enough to cause problems.
* He'd dated in high-school and during his training (mostly because of his very good looks because lol he fails at pickup lines) but pretty much swore off women not involved with Oni after Shuki tried to kill him. His type is strong, powerful women (while he's not adverse to men he is far more attracted to women) so he had a brief affair with a female Oni but they lived too far apart to really date. He also dated Midori once or twice but it never became sexual. They got into involved discussions about weapons, spells and techniques instead.
* He's had a sporadic but long-term affair with an unnamed male Oni who he only sees in person maybe once a year at New Years. This is the only man he's ever thought to have a relationship with, though he's had the stray attraction or two (and maybe an alcohol aided makeout session or two as well). Friends with benefits, and mostly as a way to deal with lifelong bachelorhood for both of them. He was too content with it to actively pursue a relationship but won't say no to the chance, especially now with all the strong, attractive women in Camp.
* He was on his own again by 23 and worked very well and hard and then somehow met Todoroki (then Todayama) (possibly saved him) at around 30 and agreed to be his master quickly.
* His own experiences made him try to be as different of a master from Shuki as possible. As a result he tended to be entirely too permissive, especially at first. He got better as he got used to Todoroki's needs.
* He discovered a great love of teaching while training Todoroki and those two years were his favorite of his career.
* He would have kept Todoroki in training for another year or more if not for his injury (the knee was the primary cause but his heart was causing problems as well) forcing him to retire. He's come to understand that this was a good thing in Todoroki's case.
* He wanted to teach Todoroki spells but Todoroki had little talent
* he prefers not to use spells often as it is easier to rely on Disk Animals and his own abilities. But he does place great value on knowing them as part of Oni heritage.
... I think that's it. Possibly more to come.