Shiromizakana (白身魚), real name Horiguchi Yukiko (堀口悠紀子), is the illustrator of Kokoro Connect. She is an animator, character designer, and illustrator from Kyoto Prefecture, and works at Kyoto Animation. Horiguchi attained fame for her work as a character designer for the popular anime Lucky☆Star, and is now primarily a light novel illustrator.
After graduating from junior college, Horiguchi joined Kyoto Animation in 2003. Her first position was as an animator for the television anime Crayon Shin-chan, and began work as a key animator for the first time on Episode 163 of Inuyasha. Her first work as a character designer was for Lucky☆Star. She has also worked on anime such as K-ON!.
Horiguchi's art style is distinctive: her unique shading technique and edgeless line tracing make her well known. 
- She is the older sister of BUNBUN, another well-known light novel illustrator. She is very close to her younger brother and was once part of a doujinshi circle with him.
- Her father, Horiguchi Fumiaki, who won the mayoral election of Yawata City on February 12, 2012. During his campaign, she supported her father by drawing his portrait in a manga style.
- She has also published under the pseudonyms "dochibi" (どちび) and "sasagiA" (佐々木A). She publishes light novel illustrations exclusively under the pseudonym "Shiromizakana" (白身魚).
- She has been highly praised by fellow animator Akai Toshifumi, who not only emulates her style but even adopted the moniker "Horiguchi God" (堀口神) when working on the anime Hayate no Gotoku!.