Kaguya-sama: Changing the way you address someone without your relationship having changed

Question

Question:

Is it common in Japanese to (temporarily? permanently?) change the way you address to someone even if your relationship has not changed because of certain intent say, you want to intimidate them or treat them as a child or something?

• (Of course ignore cases of, idk, fraud like impersonating as someone else and so you of course may have to change how you address this person. And also ignore like changing address depending on who else is around.)

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Context:

In the manga/anime Kaguya-sama: Love Is War:

Main character and female protagonist is Kaguya Shinomiya, 2nd year high school student so 16-17yo. Kaguya's crush is male protagonist Miyuki Shirogane, also 2nd year and the student council president. Kaguya's friend is Chika Fujiwara, also 2nd year. Chika has a younger sister Moeha, about 14yo.

• In S02E02, Kaguya addresses Moeha as 'Moeha-san'.

• In S03E10, Kaguya addresses Moeha as just 'Moeha'.

Image for reference:

Videos for reference:

• S02E02 - See 0:25-0:30 here: Moeha addresses Kaguya as Kaguya-chan, and Kaguya addresses Moeha as Moeha-san .

• S02E02 - See 0:48 - 1:06 here: Actually, Kaguya wanted to address Miyuki's 14 year-old younger sister Kei as Shirogane-san then Kei-san then Kei-chan before settling for just Kei. Kaguya expresses deep reluctance over calling anyone by their 1st name only. Kei is actually Kaguya's 1st time.

• S03E10 - See 0:00-0:20 here; the 'Moeha' without honorific is at 0:09 : Moeha tries to make a move on Miyuki. Kaguya tries to intimidate Moeha.

Actually, afaiu, 'Moeha-san' is too polite, but I figured it was just Kaguya's thing or Kaguya's school's thing (Quote: 'In that school, everybody pretty much uses keigo with everybody else'). But whatever even Moeha's address of Kaguya as 'Kaguya-chan' I think is atypical too. The point is that Kaguya says Moeha-san and then later changes to just 'Moeha'.

I tried asking this question How Kaguya addresses Moeha Fujiwara in some forums outside stackexchange, and they've suggested things like:

Kaguya is doing this to either intimidate Moeha or treat Moeha as a child (eg you call a younger junior high school or younger high school student as just by 1st name or least 1st name-chan) as part of Kaguya's speech of telling Moeha that Moeha is like a child compared to Kaguya and Miyuki to try to dissuade Moeha from making a move on Miyuki. (I'll forget for now the possibility of 'Moeha-chan' vs 'Moeha' and treat 'Moeha-chan' as identical to 'Moeha' here. Or maybe Moeha-chan is identical to Moeha-san.)

As to whether or not the proposed reason for dropping the -san is actually the case, that's for anime stackexchange and manga/anime forums I guess. My question is about the idea behind this possibility.

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Note: I wanted to sound like a weeb/weeaboo by saying 'imouto' to describe Moeha and Kei, but Eddie Kal wouldn't let me. Huhuhu.

Answer 1

Regarding the particular case, I think your understanding (from other sites) should be fine, although it does not necessarily intimidate Moeha. It sounds like emphasizing Kaguya's status as an elder - one who instructs, educates her juniors. In a sense, it may be like using a full name in English.

Also, using first name alone here may make it sound more like a serious advice compared with using Moeha-chan (using Moeha-san won't make much difference to me).

I think (could be wrong), temporary switching from Dex to Dexter could happen. It may imply something but could be just a whim and doesn't mean much. Things are sometimes similar in Japanese.

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Just two examples I was able to pin down from memory.

1. In Weathering with You, Natsumi calls Hodaka as Hodaka-kun, in the near last scene, Natsumi helps Hodaka run away from the police with a motorbike, which bumps into a pond, Hodaka then runs along the railway. Towards him, Natsumi shouts "Hodaka, hashire (Hodaka, run)". This dropping of kun may sound natural because it is an imperative, but does not mean a lot.

2. In Yotsuba& (vol 5, p148), Father speaks to Yotsuba (his child) with "Yotsuba-san". This is an example of addition of "san" to his own child. This could be an indication of Father being taken aback by Yotsuba's behavior, and makes it sound his seriously wondering what the child is trying to do.