Igusa is an inukami contracted to Kaoru Kawahira, distinguished by her profound shyness, especially around men and Keita Kawahira, whose nature she finds perverse. This timidity often overwhelms her, causing nervousness and fainting spells during stressful situations like her attempts to observe Keita and Kaoru for research.

She possesses dark green hair arranged in two braids and violet eyes, stands 164 cm tall, and has a figure measuring 78-56-80 cm. She is rarely seen without her spectacles.

A core part of her identity is her hidden vocation as a manga artist. Under the pseudonym Ruriko Saffron, she produces shonen manga and secretly creates shonen-ai works, a genre she personally enjoys despite her fears. She keeps this entire career concealed from her fellow inukami.

In chapter 25, her character develops when, aided by Imari, Sayoka, and Tensou, she hides inside a maneki neko statue to spy on Keita and Kaoru in a bath for new material. Overcome by anxiety, she faints before gathering any information, an act that results in collective punishment for the group from Sendan. Feeling guilty, she is later reassured by a forgiving Kaoru. Both he and Keita then grant her permission to use them as subjects for her writing, unaware of the specific genre, leading to a successful acquisition of material.

Chapter 12 further suggests she may harbor small romantic feelings for Keita, a shift from her initial fear of him before they met.

She serves as a supporting member within Kaoru's pack and is identified as a youkai deity. She is 124 years old and her birthday is December 15.