hi 8 months later
- i think (unpossessed) kazumi and satoru are basically at the same level of skill with vanguard (which says a lot about kazumi because satoru is a fuckin branch chief) so they tend to fight each other a lot at friend meetups, and if satoru is asked to do a cards exhibition and tasked with picking the opponent he always has kazumi on his shortlist of possible fighters. like he loves tokoha and kumi to death and then undead again but kazumi is a much more even matchup, so he likes turning to him if FIVA has an event that needs him to do a show fight. because they're evenly skilled (and at an extremely high skill level, at that) the imeeji from their fights tends to be much more intense and vivid than fights they have that are more one-sided in their favor; this means kazumi tends to keep a less composed face (in favor of his evil-lookin bloodthirsty grin that is actually just how he shows max excitement) and laughs and smiles/generally just seems to be having a lot of fun comparatively to his other matchups, while satoru noticeably amps up the theatrics of his imeeji (bc their fight imeeji is default nighttime i have this very specific image of satoru entering his final/game-deciding turn with a little monologue about "dawn is rising, and our encounter is coming to a close. can you survive this last vampiric frenzy?" with the battlefield imeeji going from pure night to that pre-dawn red glow) and he also (like kazumi) tends to get a competitive smirk or smiles without noticing at particularly high-stakes moments. it's like, they still love fighting everyone else, but fights just hit particularly different when you're precisely evenly matched (see:shion and chrono) and the way they have fun with each other pushes the others (like kazuma or kumi) to be like OOOHHH JUST YOU WAIT IM GONNA GET THERE ONE DAY!!! anyway this entire point was very validated by the dialogue in the zero event which made me so happy :^) i think they also have a ridiculously even win-lose score, like neither of them ever get more than 2 wins ahead of the other in their record, and they both keep track of this/know the score at all times off the top of their head even though it's less of a competitive thing and more of an injoke to smile about

• satoru has a tendency to grab someone's hand to guide them without it even being a romantic thing (him and his friend in the hospital did it for each other a lot on days where one of them was weak and needed support to walk around, he didn't grow up in an environment that was like UHMMM THATS KIND OF ROMANTIC and only figured out it's kind of weird to do from tokoha after he did it to her and her bi ass got flustered by it (if he did it to lunam or kumi before they were 100% unaffected)) but ANYWAY kazumi is also so deeply not immune to this + tends to be notably bad with directions without any assistance from a map or GPS. so sometimes satoru will spot him like 2 blocks from where he's expected to be and he's like "oh it's okay, follow me" and TAKES HIS HAND and kazumi's like ((UNCHARACTERISTICALLY SILENT BECAUSE HE HAS JUST BEEN TRIPLE CRITICAL'D)) and when they show up satoru lets go of his hand and kazuma looks at him in a I Know What You Are way while taiyou is like "onimaru-san do you need some water? your face is a little red :O"

• both of them have the capacity to stay up late if the situation needs it (work, college), but kazumi is the one who can stay up late into the night even when it's just for something leisurely like video games, while satoru tends to doze off around 1~2AM if there isn't a sense of urgency that requires him to stay up. he'll usually wake up when kazumi's getting ready to go to the bedroom and walk back to bed with him, but sometimes if he's particularly sleepy kazumi thinks it's cute to carry him to bed princess-style. satoru usually nuzzles his face closer to kazumi's chest when kazumi does this bc mmm warmnn and unlike the handholding thing he is aware he's being romantic/endearing when he does this, but does it purposefully bc he knows kazumi's heart melts at it. their late-night walks back to the bedroom are some of their most tender time spent together

• vague nsfw one for the road but theyre Absolutely the trope of "kazumi is generally louder/more talkative and satoru is quieter/more reserved but they flip those tendencies in bed" this is written in scripture actually. don't fact check me