Kanna Kii is a Japanese manga artist and illustrator who also works under the pen name Niwa. Originally employed as an animator, Kii began working as an illustrator in 2010 before making a manga debut in 2013. The debut work was the one-shot Umibe no Etranger, published by Shodensha and collected in a single volume the following year. This title, later released in English as Seaside Stranger or The Stranger by the Shore, attracted early attention for its art style and narrative approach, earning Kii a nomination in the Best New Author category at the 2015 Chil Chil BL Awards and a place on the Kono BL ga Yabai! list of recommended works.

The success of this initial story led to a sequel series titled Harukaze no Etranger, which began publication in 2014. The first volume of this sequel ranked in the top ten of the Osusume BL Comics sales chart in 2016. Kii has continued to create original manga, with other works including the one-shot Yuki no Shita no Qualia, published in 2016, and Mahō ga Tsukaenakutemo, released in 2018. In addition to writing and drawing original manga, Kii has maintained an extensive career as an illustrator, providing art for numerous light novel series and literary works across various Japanese publishing imprints since 2010.

The L'étranger series was adapted into an anime film. The Stranger by the Shore, a theatrical anime directed by Akiyo Ohashi, premiered in 2020 with Kanna Kii credited as the original story author and also serving as character designer and supervisor for the project. Kii’s background in animation has extended to other projects as well; in 2021, Kii provided the character designs for the anime film Sing a Bit of Harmony. Earlier television anime credits include providing ending illustrations for episodes of Hidamari Sketch, If Her Flag Breaks, and Shōnen Maid.

Kii’s artistic identity is characterized by a soft and delicate drawing style. The narratives, which fall within the boys love genre, are noted for their focus on slice-of-life realism. Stories often center on young adults, such as students or office workers, navigating doubt and emotional uncertainty, with a particular emphasis on the measured evolution of their relationships. Kii is regarded as part of a generation of creators who emerged in the early 2010s, recognized for combining strong illustrative skill with stories that explore introspective, character-driven drama.