Seiran Kobayashi is a Japanese actress and voice actress born on September 25, 2004. She began her entertainment career in 2009 as a child actress, gaining early recognition through a commercial for Calpis and a role in the television drama Samayoi Zakura. Her early work included numerous television dramas and films, often playing the younger versions of main characters. In 2012, she also debuted as a singer, forming the duo Star Flower with her friend Kanon Tani.

Kobayashi transitioned to voice acting in 2014 with a role in the anime Space Dandy. Her first leading role as a voice actor came in 2018 when she was cast as the protagonist, Oriko "Okko" Seki, in the anime television series Waka Okami wa Shōgakusei! (Okko's Inn) and its subsequent film adaptation. This performance was particularly special to her, as she had enjoyed reading the original Okko's Inn novels as a child.

She has since taken on a variety of notable voice roles in both anime series and films. She voices the young girl Eri in the popular superhero anime My Hero Academia. In the Star Wars: Visions anthology series, she played the lead role of Lop, a bunny-like alien girl, in the episode Lop & Ochō. Kobayashi was also a guest cast member in the 2021 film Eiga Healin' Good ♥ Precure Yume no Machi de Kyun! tto GoGo!, where she voiced Kaguya, a well-known model and the popular "Yume Aaru Princess". Beyond anime, she has worked on foreign dubs, such as providing the Japanese voice for Young Nala in the 2019 version of The Lion King.

In addition to her acting work, Kobayashi has appeared as a narrator and MC on various television programs. She is described as having an expressive and distinctive voice, and is known in the industry for her work ethic.