In the last chapters Touka seems to always be wearing the same white T-shirt, however, depending on the time and situation, Ishida decides to emphasize the forms that are include on the top:
In chapter 122 Touka wants to have time alone to talk with Kaneki, therefore the shirt that she wears consists of shapes similar to those of an hourglass
Hourglasses
are often used to symbolize “ time”, even at windows computers one can set the mouse so that the waiting icon takes that form.
In chapter 125 Touka wears the same t-shirt but with Y forms at the top, this could be linked to the chapter title “X:”
In genetic, the masculine gender consists of XY chromosomes, this could be indicating two things to us: first that probably the son was conceived that night (good job Kaneki), and second that probably the child will be a boy.
In chapter 135 Touka wears the same T-shirt with four-leaf clover shapes at the top
As i explained in an earlier post, the four leaf clovers are representative of good fortune and hope, indicating a possible positive result to the conflict that is happening right now.
Although one might think that the forms on that T-shirt are due to the artistic style of Ishida, in my opinion and based on the approach that he puts while drawing them, makes me think that not only aren’t for chance, but that they intend to launch a concrete message depending on the situation and the moment.