Shizuka first manifested near Aomori's coast during Kokona Otori's childhood acting practice, emerging from Kokona's subconscious desire to improve. Initially unaware she was Kokona's "Sense" — a supernatural manifestation tied to acting talent — Shizuka coached Kokona until her skills advanced, then vanished despite their promise to become World Dai Stars together.

Years later, when Kokona repeatedly failed auditions due to lacking a Sense, Shizuka reappeared. Now understanding her nature as Kokona's Sense, she concealed it, fearing Kokona's disbelief. Shizuka became Kokona's constant support, managing daily routines, homework, and acting guidance. Physically, she possesses medium-length dark blue hair with a yellow clip, round blue-turquoise eyes, and often wears Utagawa High School's uniform with a blue cardigan and pantyhose, or casual grey-blue sweaters with green jeans.

Her personality blends analytical calm with confident dominance, serving as Kokona's emotional anchor. Frequent nagging earned her a "mother" reputation within Sirius troupe, pushing Kokona forward during doubt even at personal cost. This self-sacrifice culminated during *Phantom of the Opera* auditions, where she deliberately disappeared to resolve creative conflict and force Kokona's independence.

Shizuka's relationship with Kathrina Griebel shifted from initial dislike over Kathrina's harshness toward Kokona. During Sirius' *Tale of the Bamboo Cutter*, Shizuka willed herself corporeal as the moon messenger primarily for Kokona's benefit. She then openly identified as Kokona's Sense, integrating with Sirius and bonding with Yae while remaining Kokona-focused.

Her final, permanent return occurred during Sirius' *Phantom of the Opera*. Kokona's emotionally charged performance reconnected with her, allowing Shizuka to fully materialize onstage and fulfill their childhood promise to become World Dai Stars together. This ended her cyclical vanishing for Kokona's growth, cementing her existence as both Sense and independent performer.