
Can anybody explain to me how did shinomiya got that eyes?

Narumi's eyes isnt the only eyes that they have from #1. #1 monster had numerous eyes so when it was eliminated they ofc harvested alot of it's eyes (like other monsters they also get like core parts that can be used for weapons/armour etc) The ones that are shared by Narumi and Shinomya is their vision. Since both their modified eyes came from the same monster they are able to make it function as one.
im just here breathing and loving this story both in novel and in manhwa. one of the best!