As you may already know, when you do the Shikoku Pilgrimage, one of the “traditions” is to have a book with you (or sometimes even a large scroll) that you get signed by a beautiful calligraphy of the temple’s name at each temple where you stop. This is not unique to the Henro pilgrimage by the way.
Usually, it’s a monk who does it, but not always apparently. As the picture was taken in Zentsu-ji, the largest temple of the Shikoku Pilgrimage, maybe they have extra-staff helping. Unless nuns in Zentsu-ji don’t have to shave their heads. I have no idea.
In any case, know that when you visit any of the 88 Shikoku Pilgrimage temples, you too can have a book signed. It will cost you 300 yens if I remember correctly (I haven’t had it done in quit a while, I forgot).