Yamaguchi Chihiro

Yamaguchi Chihiro (山口千尋) was a Lily who attended Yurigaoka Girls' Academy. She was one of the four founding members of Legion Sanngriðr along with Kondo Misaka, Imagawa Homare, and Kiko Totori. After a certain incident, she was declared to be killed in action, though her body was never found. Later, during the Oshima Nest Incident, a Lily referred to as Kou no Hana appeared, seemingly possessing the same magi signature as Yamaguchi Chihiro.

Personality
Despite her interest in poetry, Chihiro was not known to be a woman of many words. She did not open up easily to others, though some, like Imai Seira, managed to make it happen. She was, however, known for possessing a keen intellect, and was said to be meticulous.

Early History
Chihiro apparently came from the GEHENA lab at Kuramayama, specifically for use in the 13 Sisters Project. Before the project could begin in earnest however, Kojima Nadeshiko took her into her "custody" and brought her to Yurigaoka.

Once at Yurigaoka, Chihiro enrolled in the kindergarten program, where she made fast friends with Misaka, Homare, and Totori. In particular, Chihiro's relationship with Misaka was quite close, the two of them forming a partnership where, while Misaka was known for power and spirit, Chihiro was known for her speed and strategic acumen.

The four friends would go on to swear an oath to form a legion together in the future, so that they could fight alongside each other.

Though her partner Misaka wanted to become the next Brynhildr, Chihiro herself was never interested in Yurigaoka's politics. Instead, she remained a steadfast supporter of Misaka's ambitions. Notably, Chihiro was Misaka's strongest supporter for becoming the captain of Sanngriðr, believing it would aid in those ambitions.

Special Small-type Swarm & Death
When older, Chihiro oversaw a group of Yurigaoka kindergarten students during a training exercise, along with the slightly younger Lilies Luise Ingels and Hayami Katsura. The group ended up wandering outside of the academy's walls, an accident that proved fatal. A mass of special small-type Huge suddenly converged on the group, attacking in wild and unpredictable ways, as if driven to a frenzy. Despite the three older Lilies fighting fiercely, the group was overwhelmed, as it was largely composed of kindergarten students who had never been in a real fight before. Multiple casualties arose, some of the students unable to go on and become Lilies afterwards.

Chihiro for a time fought to stem the tide alone, but despite taking down a great number of the swarm, she died before help could arrive. Her body, however, was never recovered. With only her blood-stained CHARM left behind, she was ruled killed in action.

Oshima Nest Incident
During the Oshima Nest Incident, nine Boosted Lily "Remnants" (成れの果て) called the "Flowers of the End" appeared, and among their number was one referred to as Kou no Hana. When Kondo Misaka clashed with Kou no Hana, she felt her magi was identical to that of her dead friend and partner, Yamaguchi Chihiro. Likewise, Kou no Hana began to regain her sense of self through sharing (via repeated battle) Misaka's magi. She responded to the name Chihiro, and recognized Misaka. However, she never fully came back to herself, instead seeing only that she had been "replaced" at Misaka's side by another—Hasebe Touka. She turned her rage and jealousy onto Touka thereafter.

The fate of Kou no Hana remains to be seen.

Trivia

 * Chihiro enjoys poetry. She prefers waka poetry in specific, and is also familiar with Chinese classical poetry.
 * Her favorite food is wagashi, a kind of Japanese sweet.