hello!! mizusaba's gender is not indicated in the japanese text. they're never referred to with any gendered terms, and they also don't use any gendered terms about themself either. this is what we know:

• mizusaba speaks similarly to ibuki (using wa~ as a first-person pronoun and "sa~" or tildes at the end of their sentences)

• at one point, kanata compares mizusaba to madara (when mizusaba explains their presence in konata's life, kanata says it's "like what mikejima was to me in the past")

• when kanata greets mizusaba in okinawan by saying "haitai", mizusaba replies back with the same greeting, then informs kanata that he doesn't have to speak okinawan with mizusaba. "haitai" is the greeting used by okinawan women, whereas "haisai" is the greeting used by okinawan men. since kanata was first to use the greeting, it's not clear if this was an error on the writer's part or not

all in all, unlike other prominent NPCs that were introduced in climax stories, there's no true clear indicator of their gender. JP fandom noticed the ambiguity, and have been debating about mizusaba's gender based on the information we have. this is likely why you're seeing "brother" and "sister", because technically, it's all up in the air right now

at first, my tl used he/him pronouns for mizusaba because of the madara comparison, but then i realized it was entirely assumptive on my part, so i've changed to they/them so that people are free to interpret mizusaba as they like. the JP fandom have been doing the same and interpreting however best suits their vision of mizusaba. i hope this helps clear it up!

submarine started it all (but doesn't have much to do with ibuki's family except the tiniest "strained back" grandpa hint), supervillain mentions quite a bit about okinawa, and then stella maris delves pretty deep into it! i hope you enjoy reading, it's an intriguing storyline!!

fun fact there's even a new okinawan restaurant near ES now, this was revealed in fine's climax event lol not sure if it's based on the exact same restaurant as ibuki's grandpa BUT it does use the same background as that restaurant! (on that note, fine climax event is a bonus story to read since it's related to stella maris)

hmm... i read back on the lore we've been given and it seems like they're a family with a lot of influence around okinawa, to the point they were even appointed as the point of contact with hoshijima, even when it was a confined land

in regards to their relationship with hoshijima, the label mizusaba gave his family is "mediators" and "point of contact", rather than protectors. when ryuseitai try to learn more about the hoshijima residents, mizusaba explains to them that they're just ordinary people with a unique religion, which sounds to me that he's speaking as an outsider of the group. he also mentions that he doesn't actually have connections with the hoshijima residents (save for konata). this is my own interpretation, but it implies to me that mizusaba's relationship with konata is more of a personal one, hence why he tends to try and help him.

that all being said, there may be way more to their backstory and origins that we still don't know. the farthest we know is that their grandpa was a feared pirate around okinawa (i tried to search where akira got this inspiration from, and only found one historical figure but not sure if that's where it's from... yet) who eventually settled down as he grew older. they also use a lot of okinawan dialect, and from my own interpretation, i noticed that ibuki sees himself specifically as an okinawan (with american influence) rather than a "japanese person" born in okinawa. what i mean by this is that there's a clear distinction being made here, even though okinawa is still a prefecture in japan.

i hope i'm making sense...... this was basically just me presenting the information we know so far, but also, just like you, i'm wondering what this means about their origins, because there is still a lot we don't know yet. it makes me want to find books on okinawa and learn more HAHA i'm so curious and intrigued.

(will compile all of this in a more concise post soon!!)

the ones in hiding (or rather just don't interact with the public much) are the people of hoshijima, the oni family is well-known around okinawa! even have a restaurant that mizusaba is cook for (and their grandpa used to work in until he strained his back)

the series of events you wrote about the event stories is correct yeah!! hoshijima is a small island near the okinawa main island, so yes supervillain happened in okinawa main island, whereas stella maris went back and forth between the small island hoshijima and the main island.

hoshijima people have connections with the okinawan/oni family (but not necessarily the vigilante group...?), as they act as the mediators and the ones who send them supplies. it used to be the grandpa who'd send supplies, then became mizusaba! mizusaba mentioned that he's not a worshipper or anything, so i think they might not have anything to do with the religion per se...? hmm

yeah i'd like to make an easier way to understand all this information as it's a lot and scattered everywhere between the event stories, so thank you for asking 😭🙏

i think they're an interesting dynamic! i like tetora's dynamics and i think he's very versatile and works with many people, i'm glad to see that akira is willing to expand his circle as always and show us more new sides to him. i love the way ibuki brings out a more serious, dependable and confident tetora.

i love how his interaction with ibuki is entirely due to who tetora is as a person (choosing to take down crimpro for his own self-worth), which makes his relationship with him unique and special.... vs something like tetora vs rinne, where a lot of people feel complex feelings about rinne for various reasons, and tetora is just one of the many who do. so i'm a big fan of how their dynamic exists purely because it's tetora and his own decisions and lifestyle.

all in all very excited for what new things we'll get to see for tetora through this. like wow, i can't believe akira used ibuki's idol story 2 to tell us new karate club lore LOL that gives me high hopes for their future content!! i also wonder how much it'll influence ibuki's side and his character development. lots of things to be excited about

hi art! o7

here's a run-down of ibuki (not the full list):

• oni originally referred to ibuki's grandpa, and eventually became about him too

• ibuki calls himself the descendant of oni, likely because he is the "2nd generation of oni". the 1st generation is his grandpa. hence being a descendant!

• ibuki is mizusaba's younger brother, but ibuki is so respected and reliable in the community that he's everyone's "big brother", so even mizusaba calls him by an older brother naming

• it seems ibuki got interested to go to japan thanks to niceP's invitation. after arriving in japan and presumably meeting up with niceP (idol story 1), he somehow hears that crimpro got taken down by tetora, so he tries to go meet tetora to learn more about him

note: from here on is my own personal attempt to compile the events!! i'm talking based on my own understanding of the events

prior to supervillain and its events, the oni vigilante group and crimpro were enemies, and the oni group were the first people to go against crimpro and take them down. after defeating crimpro, the group disbands likely because the boss goes to the US. (this "went to the US" boss is very likely to be ibuki). this seems to have weakened the group since then (supersized villain ch5)

in idol story 2, ibuki doesn't fully confirm to tetora he's the boss, but based on the information we know and their dialogue in the story (boss went to the US, group had a descendant of oni), it should be him anyway? which means he was part of taking down crimpro the first time around.

by the time supervillain happens, crimpro revived itself, and became a LOT stronger than before because it fed on the okinawans' fear and hatred of ES. it became so strong in okinawa that even the members who were previously in the oni vigilante group joined crimpro. (supersized villain ch6)

this is the part that tetora mentions to ibuki! tetora seems to hold conflicting feelings about his decision to take down crimpro, and one of them is because he feels like he may have "a lot of unsettled business" (stella maris hidden island 2). while he's glad that the evil crimpro was defeated, he feels like he might have made people who weren't 100% evil suffer in the process (he mentions these conflicting thoughts in supervillain, supersized villain ch15), so it tends to weigh on his mind. this is shown in stella maris, where he constantly fidgets whenever he's reminded of his time as a spy for crimpro, and even says he sees it as his dark past.

so when tetora learns ibuki is the boss of the vigilante group, he wonders if ibuki's here to take revenge for hurting those vigilante members that later on joined crimpro. it's hard to tell ibuki's feelings on this as he just says he won't take revenge because it's old-fashioned... but after getting a chance to throw a deadly kick at tetora and seeing tetora dodge it, he seems to be satisfied that tetora is the real deal. hence saying "i'm sure even the guys at crimpro were happy to get taken down by you" (which implies even the vigilante members who joined crimpro were "happy" about it too!)

beyond this, i'm not sure haha. this is my own interpretation, but it seems like ibuki gave tetora a reason to have beef with him (throwing sneak attacks on tetora in a "villain-y" way?), while ibuki feels satisfied enough to know tetora is genuinely strong (and potentially even capable of "exterminating" him, the ogre?). in his introduction quote, ibuki says that "he'll be looking into things with his own eyes and confirming it for himself", so that adds up with how he acted with tetora!

what makes this a bit confusing is that the vigilante group seems to have been called "oni", and the boss himself was known as oni too because of his ancestry. this is again my own interpretation, but i assume the oni family (ibuki and ibuki's grandpa) was just that influential, that even a whole group led by one of them is called oni.

hopefully i didn't miss anything crucial. the lore is scattered across various chapters and stories, so it can be a bit tricky to compile. i hope this helps and let me know if you have any questions!!

stories i referenced: ibuki idol story 1, ibuki idol story 2, supervillain, stella maris, ibuki's introduction quote