Heidi

Heidi (ハイディ Haidi) is a Gutenberg of Ink.

Appearance
Heidi appears young for her age and when Myne met Heidi, she assumed Heidi had just come of age even though she is over 20 years old. She has reddish-brown hair that is tied into a single braid and twisted into a bun and grey eyes that are filled with curiosity.

History
Heidi is the daughter of an ink maker, Bierce, and joined his ink workshop when she was baptised. During her apprenticeship another apprentice was told to look after for her. This apprentice was Josef who ended up marrying her.

Personality
Myne comments that she thinks Heidi is "funny and hard working, but kind of weird" to which Lutz replies "... You are one to talk". Benno also tells Lutz that he now has two Mynes to look after showing that everyone who knows both of them think they are alike.

Heidi focused on ink and is very curious to find out why the ink colour changes when making it rather than finding out how to make more colours.

While she is focused on discovering new ink, she does think about the future and her husband. This is shown when she asks her husband, Josef, to get his beruf certification once the work with coloured ink was completed. She hurried the research and worried about the research to lessen his burden and support him.

Story
After Myne sells the method of making black printing ink to the ink guild, Heidi wanted to immediately begin research into other colours. Her father, Bierce, stopped her since the sale was done using a magic contract and he was worried that Myne had sold coloured ink elsewhere with a different magic contract. Heidi then pestered her father until he agreed to set up a meeting to talk about coloured ink.

At the meeting, she was very eager to begin talking about ink and had to be restrained, along with Myne, until the talks were finished. Once an agreement was reached she immediately invited Myne to her workshop. There she began making coloured ink with Myne's instructions. The ink colour changed in unexpected ways and it seemed to be more dependent on the oil used rather than the powder added. However, with time and perseverance, enough colours were created to satisfy Myne.

Next was to test the ink on paper and layer the ink over each other. Initially the ink faded when applied to paper. Trombe paper was less affected. . When the ink was layered, it became very dark, almost black. This problem caused Heidi to lose sleep and sleep-walked into a paint workshop while thinking how they layered their colours but she did not find out the secret. Myne discussed the problem with her mother and found out about fixing agents and how they keep colours vibrant and allow them to be layered. However, this was from a dyer's perspective and Myne was worried about how the process would transfer. Myne later discussed fixing agents with Rosina who instructed her how to use fixing agents for printing.

Having found enough colours and how to print with them, Heidi's mood dropped as she thought she would no longer be allowed to continue her research. Myne, however, agreed to continue paying for research, but sets a limit; if they are ever late with an ink delivery then she would cut the funding.

Trivia

 * Miya Kazuki says that she wrote Heidi and Josef imagining what might have been between Myne and Lutz if Myne didn't have the devouring.
 * Due to Heidi's exuberance, she is not allowed to interact with customers.
 * She is jealous that the leherls could eat where Bierce wouldn't watch them constantly.
 * Heidi is the only person receiving the title of Gutenberg who openly expressed happiness about being bestowed with it, jumping with joy.