There's also 'Citrus Hearts'. It's great because it focuses on the relationship between the characters in a very emotional and detailed way. The author does a wonderful job of showing their growth and the challenges they face in their relationship.
You can try fanfiction websites like Archive of Our Own (AO3). It has a vast collection of fanfics from various genres, including citrus anime fanfic. Another option is FanFiction.net, which also has a good number of anime - related fanfics, so you might be able to find citrus anime fanfic there as well.
You might try looking on fanfic - specific websites such as Archive of Our Own (AO3). It has a vast collection of fanfics on various topics, so there's a chance you could find 'citrus principle fanfic' there.