- Ink was original planned as a contemporary book, with Tomo being the first character that Amanda Sun thought of.
- Due to Amanda Sun's background in archaeology, Egyptian Mythology also had a big influence on the series. She has said, "I learned that the scribes who painted the hieroglyphs on the tomb walls would often paint or chisel jagged lines through the middle of any glyphs that had snakes in them... So the snakes wouldn't come alive and bite the entombed Pharoah in the After Life. I loved the idea that drawings could come alive in such a dangerous way. I combined this idea with the origins of Japanese kanji (characters) as a way to communicate with the spirit world and the ink was born..."
- Katie was originally a character in a Star Trek fan fiction by Amanda Sun.
- In an outtake from Ink, Katie follows Tomohiro to Toro Iseki (like normal) but gets caught by a security guard patrolling the fence. The guard eventually gets flustered when he realizes she is a foreigner, and lets her go with a warning. Sun as said, "Authoritative figures in Japan are often very reluctant to correct foreigners if you make mistakes... So when this event happened in Ink, Katie again felt isolated and out of place because of the special treatment."
- In Ink, Jun asks Katie who her favorite classical composer is (to which she replies Beethoven. However, is interest goes far beyond that, as he plays a classical instrument! Which one will be revealed in Book 2! Concerning Jun's hobbies, Sun has also said "Music is only one of Jun’s hobbies. He also loves police dramas on TV, kendo, and Italian food. He enjoys Korean food and café au lait too, when he’s not busy getting into trouble."
- In Shadow and Ink, Katie talks about a little town in Canada where her grandparents live—Deep River. This is actually were Amanda Sun grew up!
These pieces of trivia come from here!, an interview with Amanda!
|"An enjoyable peek at a world very different from America, yet inhabited by people whose hearts are utterly familiar."|
|— Publishers Weekly|
|"The unique setting and observing how Katie learns to live in... foreign surroundings... make this story special."|
|"The descriptions of life in Japan... create a strong sense of place, and set an exotic backdrop for this interesting series opener [talking about Ink] by a debut author."|