Two part question

[Christopher]

Figured this is where to put it.
1) Should there be a comma right after Ryuko? Ryuko, Volume 1 does so that is why I'm asking.
2) Can the description be changed from German to English? The Kindle edition is in English.

[Arenda]

Done

There is not a definitive answer about the comma in the Librarian Manual.
The relevant section about series names in title when the series title is also the title of the book, says:

An exception to this is when the series name is the primary or only title. In this case, the title may be formatted with series name and number as the title (the number may be written out to match the title as shown on the edition) and any additional title text as the subtitle.

Examples of books with the series as the primary title:
My Brain Hurts, Volume One
Gun Smith Cats Vol. 3
https://help.goodreads.com/s/article/...

One of the examples has a comma, the other doesn't. Personally, for cases like this I prefer a comma.