|Japanese Name: 九谷焼リカコ|
|Romaji: Kutani Rikako|
|Date of Birth: August 11th 1990|
|Age: 21 (22)|
|Japanese VA: Itou Miki|
|English VA: Tracey Rooney|
Rikako is the fraternal twin sister of Shirou Kutani, it is later revealed she is actually 22 years old and was really pretending to be Shirou's sister for the sake of an experiment.
Despite her young appearance Rikako is actually twenty-two years old and is only having to pretend to be Shirou's fraternal twin sister.
Rikako has a tomboyish personality however acts more mature than Shirou. She acts friendly towards Saya and often scolds her brother and can drag him around, however Rikako can have her childish side but never the less she is loyal. It is later revealed that she is actually 22 years old and is not actually Shirou's sister however she decides to help them and in the end she decides to become his honorary big sister and he becomes her honorary little brother and they forgive each other. Though often teasing her brother she deeply cares for him however a running gag is that Shirou is constantly at odds with Rikako. However she adores Saya and asked her to call her "Rika-senpai" whilst she calls Saya "Saya-chan" the two get along well and Rikako acts like an older sister towards Saya often comforting her or giving her advice.
Rikako is a short young woman with dirt blonde hair and has brown eyes. She wears a brown sleeveless top and a white long sleeved hoodie over it with khaki shorts and a matching jacket with brown boots.