This truly is Takagi Ryo's work, though I don't think that his art style is very similar to Chitose Piyoko's. Chitose sensei's characters tend to be a lot slimmer, with slightly narrow faces...
No. I don't mean all of Takagi Ryo's work is similar to Chitose Piyoko's. Just this one. That's why I was asking.
Might just be the style. A lot of mangakas used this art style back in the 90s and 2000s, around mid 2008 the popular style changed to what her current work is.
Just look at how her style changed through the years just on the cover art.
https://www.mangaupdates.com/series.html?id=2894
The art looks more like Chitose Piyoko's. I haven't seen this style in the other works by this mangakas. Is this manga truly Takagi Ryo's?