At the beginning of Volume 5 of Genshiken, Saki comments on Ogiue’s clothing, telling her that if she wore clothing that fit better Ogiue would look much cuter. While we know that at the end of the chapter Ogiue made one failed attempt to revise her wardrobe, what we can see in later chapters is that Ogiue did indeed take Saki’s advice to heart. It’s something not immediately noticeable, but her clothes do start to fit better and become a little more feminine (though still boyish most of the time), especially after she starts to date Sasahara. This ultimately culminates into the outfit that Ogiue wears to Sasahara’s graduation, one of the few times we ever see her in a skirt (the first time is at dinner celebrating with everyone on a doujinshi well-sold).

Some visuals: