Either this turns Nayu-tan into a boy, or Mahiro starts to revert again. Possibly both.

Or, this makes Nayu-tan's bust grow.

Or the way i see it. The drug was specifically made only for Boy > Girl transformations. So if used on a girl....makes her more woman?

Boy → Girl seems possible but given the symbol is ⚥ I think it should be reversal, specially given nayu-tan huge reaction.

I... Okay, I was not expecting her to mess up like that. How are they gonna explain the 2-for-1 elephant special to the others?!

Tetsamaru said:

Or the way i see it. The drug was specifically made only for Boy > Girl transformations. So if used on a girl....makes her more woman?

That would be the real-world logical reasoning, but this probably works like a Belt of Reverse Gender because gender-bender logic.

I still think Nayutan is probably like a college-age female assistant of Chitose that is being given "a second chance to experience youth" because she was a shut-in the first time, not a gender-bender, herself. (Although it's possible she's just literally Chitose's little sister, the quotes around 'onee-chan' are purely to be a red herring, and she's her actual apparent age as well...)

NWSiaCB said:

That would be the real-world logical reasoning, but this probably works like a Belt of Reverse Gender because gender-bender logic.

I still think Nayutan is probably like a college-age female assistant of Chitose that is being given "a second chance to experience youth" because she was a shut-in the first time, not a gender-bender, herself. (Although it's possible she's just literally Chitose's little sister, the quotes around 'onee-chan' are purely to be a red herring, and she's her actual apparent age as well...)

i have to check back in the series, but i'm pretty sure it was confirmed Nayu was Chitose little brother

Zankyo said:

i have to check back in the series, but i'm pretty sure it was confirmed Nayu was Chitose little brother

I recall it as Nayuta being an awkward kid that was hanging out in the library. (Though, Nayuta still sounds like a more masculine name to me.)

Edit: Rereading from volume 5, it looks like Nayuta and Chitose are (likely) siblings, and (most relevant) that Nayuta's not good with people her own age.

Zankyo said:

i have to check back in the series, but i'm pretty sure it was confirmed Nayu was Chitose little brother

Well, the only time it's directly addressed is here. Nayutan calls Chitose "onee-chan" in quotes, but Japan's use of such titles isn't contingent on actually being related, and Chitose says she's "a brat I watch over at home", and that Nayuta's calling her 'onee-chan' is "self-proclaimed", which means she's expressly saying they're not related.

Also, I've been waiting for this shoe to drop the whole time, and at no point has Nayutan ever been confirmed to be originally male. In the page after the one I just linked, Mahiro even comes to the conclusion she's just a normal middle school girl, and Nayutan goes "gee I don't know about that heheh", which can certainly be used to string along someone convinced Nayutan is originally a boy, but is being reeeally cagey about it, and can easily be revealed later to just be Nayutan just teasing Mahiro and having no further meaning than that.

Basically, the author's been very, very deliberately giving us nothing concrete on Nayuta, which naturally would lead to trying to some sort of surprise reveal later on. The law of drama says the truth will be whatever the story is trying to lead most people away from presuming. The series has certainly been giving enough mixed messages lately that it's not as easy to predict, but early on in particular, it leaned hard on getting people to presume that Nayuta was another gender drug test subject, and it may be counting on readers keeping on with that implication until conclusive evidence to the contrary shakes them off even while giving mixed messages in the meantime.

Again, nothing concrete, but there's nothing in the text I recall that is actually inconsistent with this kind of reveal.

NWSiaCB said:

Well, the only time it's directly addressed is here. Nayutan calls Chitose "onee-chan" in quotes, but Japan's use of such titles isn't contingent on actually being related, and Chitose says she's "a brat I watch over at home", and that Nayuta's calling her 'onee-chan' is "self-proclaimed", which means she's expressly saying they're not related.

The 'Self proclaimed' part is virtually certainly pointing to assistant, not to 'oneesan'. Also "brat" doesn't really feel like an accurate translation of 「ちびっ子」.

And then there's an extra chapter at the end of volume 5 (not available here) where Nayuta and Chitose are talking, and Nayuta indicates not being good with people around her age.

Edit: Also, Nayuta didn't use quotes around おねーさん -- she used marks for emphasis.

If Nayuta were another drug-induced gender swap, wouldn't she be able to recognize the bottle of the drug she's (presumably) been taking voluntarily on a regular basis?

My theory is that she helps with other drugs, instead. She doesn't recognize the gender swap drug because she's never actually seen it before - only the final result, via Mahiro.

GaijinGamer said:

If Nayuta were another drug-induced gender swap, wouldn't she be able to recognize the bottle of the drug she's (presumably) been taking voluntarily on a regular basis?

My theory is that she helps with other drugs, instead. She doesn't recognize the gender swap drug because she's never actually seen it before - only the final result, via Mahiro.

Nayuta mistook the container for energy drinks that Chitose drinks.

My read of expression+reaction sounds are that Nayuta only realized the significance of what she drank *after* drinking it.

さくら said:

Nayuta mistook the container for energy drinks that Chitose drinks.

That's kind of my point, though. If she took this medicine regularly, she wouldn't mistake it for an energy drink.

GaijinGamer said:

That's kind of my point, though. If she took this medicine regularly, she wouldn't mistake it for an energy drink.

For other reasons I lean towards Nayuta's probably not taking it (and probably is the age she appears to be). But even if she were, she might be taking it in a different form. For example, like when Mihari put the medicine in Mahiro's food the first time (the way that reads it was added to the food, and not a separate drink). Only the second and third doses Mahiro took of it were (confirmed to be) in those bottles.

That kind of container is also pretty common for energy drinks IRL and in anime/manga.