Basically for ¥13,440 yen (which is 4200 more than the normal price), you get:
1) The game in a cardboard box.
2) Two nendoroid petits.
3) Arrange OST CD.
4) Tsugumi Dakimakura (not that pic in the sample image. It will be a different illustration)
5) Bekkankou’s line art illustrations for all of the ingame CGs (booklet).
6) 100 Coloured Page Booklet with exclusive artworks.
But it doesn’t stop there.
There’s Tokuten goods: (you get these only if you pre-order)
And the way you pre-order is the same for any one of these shops. Send an email to ORDER@YOKATTAWEB.COM based at this website: [yokattaweb.jp]
Then ask them if you can preorder this game, 「大図書館の羊飼い」 and tell them the shop you want to preorder it from (e.g. Sofmap.com). They will then ask you to put in a deposit. Do that. Now you have pre-ordered!
At a later date they will ask you to pay for shipping. They charge a flat rate 700yen which is THE CHEAPEST PROXY I KNOW, even cheaper than tenso.com. Yokattaweb.jp service is fairly good. I’ve used them several times. Sometimes the guy goes on vacation and that’s when response time becomes really sloppy.