Misumi Ikaruga, a member of Mankai Company's Summer Troupe, established himself as an energetic and eccentric presence by moving into the company dorms without prior permission. His defining obsession is an intense fascination with triangles, which infuses nearly every aspect of his speech, behavior, and interests. He frequently incorporates the word "sankaku" (triangle) into sentences and exhibits immediate enthusiasm upon encountering triangular objects.

He possesses light blue-tinged purple hair, yellow-orange eyes, and a distinctive mole beneath his right eye. His typical attire includes a black hoodie featuring three prominent yellow triangles on the front, complemented by multiple ear piercings. His physical abilities are exceptional, allowing him to execute gravity-defying feats like running along walls and ceilings, often triggered spontaneously by thoughts of triangles.

Raised by his grandfather who taught him acting fundamentals and gifted him a significant triangular ruler, Misumi experienced loneliness after his grandfather's passing. This loss influences his reflections on whether his grandfather observes his acting achievements. He communicates with neighborhood cats and shares this ability with troupe member Hisoka.

Within the troupe, he perceives similarities with Masumi due to shared name suffixes and facial moles, though Masumi often rebuffs these comparisons. He deeply admires Summer Troupe leader Tenma Sumeragi, noting Tenma's resemblance to his brother Madoka, particularly their prodigious talent and caring natures beneath initially standoffish exteriors. He frequently engages Sakuya Sakuma (Spring Troupe) in practice sessions and triangle-hunting excursions, drawing energy from their interactions. He seeks art mentorship from Kazunari Miyoshi (Summer Troupe) for triangle-drawing skills and enjoys sharing his triangular collections with his roommate, Kumon Hyodo (Summer Troupe), appreciating their morning and evening routines.

His activities often involve triangle-related quests, like searching for new "triangle homes" or dedicated searches for misplaced precious triangular items. He associates onigiri (rice balls) strongly with triangles, frequently requesting them from Omi Fushimi (Autumn Troupe) or making them himself, expressing distress when they lack a triangular shape. His dialogue is peppered with triangle-centric exclamations and songs of his own composition.

His acting development intertwines with personal growth. Initially focused purely on the joy of performing with his troupe, he gradually becomes aware of the audience enjoying their plays through online streams and live performances. This realization deepens his dedication; he expresses a desire to make audiences happy through acting, acknowledging this as an evolution beyond his initial motivations tied to his grandfather. An interview highlights this maturation, where he consciously reflects on conveying his genuine self while considering the audience's perspective, guided by the Director.

He actively participates in Summer Troupe productions, taking roles like Scheherazade in "Water Me!", a swashbuckling captain in "Captain Sky’s Pirates", and a reclusive character in "Love Out of Left Field". His unique physicality and triangle-inspired ad-libs frequently influence his performances. Backstage, he incorporates triangle-themed movements into stage combat exercises with Sakyo Furuichi or discusses muscle training with Tasuku Takato (Winter Troupe), focusing on the triangular shape of the deltoid.