On the wiki it states: "However, one of the homepage lines of Sanae Katagiri's "Inochi Moyashite Koiseyo Otome" SR hinted that Nana is older than Sanae, which changed most fans' speculations that she could be 29 years old or even older." what was the line hat implied nana was older than sanae??
I believe it would be this line “ 今回もあたしが最年長 ! …あれ、菜々ちゃん？どうしたの、汗かいて？” -> “ I’m the oldest this time too! …Uh, Nana-chan? Why are you sweating?” Considering Sane is 28 years old, it’s possible Nana might be even older than anyone thought.
If you ask me, I don’t think it should be taken too seriously. Nana is always nervous when age comes up and she’s already out of place with the other women. If she were actually older than Sanae she would be one of the oldest in the whole company! (only beaten by Shino and Reiko)