This is a reproduction of the packed lunch used by the "Tokyo Imperial University Sakushima Laboratory" that appears in the play, and the word "Sakushima Lab" is also on the package. The contents were kinako cream and red bean paste.
Some people who actually ate it commented that "the fragrance of kinako and the bean paste match and it is delicious" and "the kinako cream and bean paste are packed tightly and are delicious".
If you see it, why don't you take it in your hand as if you were a member of the Makushima Lab?