So, I read the creator comments on the last page and here's the gist:
The creator was one of との屋 (とのたに) (Tonoya aka Tonotani) biggest fans. They found themselves visiting Tonotani's creations often and visited the store a lot, often waiting in anticipation for the next work. Tonotani eventually came to remember this fan and they ended up becoming best of friends (going out to bars, karaoke, etc). They also did some work together and the creator helped on some of Tonotani's creations as an assistant.
Unfortunately, Tonotai seemed to have passed away. This creator made this fanbook in memory of Tonotani and hopes that someday, somehow, it will reach Tonotani in heaven. The last sentence states that he will always be Tonotani's #1 fan.