Seira has a personality similar to Lucia, considering that Seira's heart was always with Lucia. She always seems to be happy and supports Lucia everytime one of her heart fragments are attained. She loves to sing, considering how she was singing in episode 52, despite the tense atmosphere. She loves ice cream down to the core.
Seira resembles Sara in multiple ways, from the spelling of her name to her looks and gestures.
- Mermaid Form: Seira has light waist-length orange hair and orange eyes. She wears an orange shell bra and her tail is orange. Like most of the mermaids, she has her shell pendant around her neck and a few bracelet accessories.
- Human Form: Seira's hair color and eyes are a darker orange color, but her hair length varied in two episodes.. Seira's wardrobe consists of an orange dress with orange heels and the female's school uniform.
- Idol Form: Seira's idol form is a shorter version of Sara's idol form. It consists of a short orange dress with yellow frill trim accompanied with a large yellow bow and frilly orange gloves and boots. Along with the transformation, she gains her usual accessories and microphone.
Seira can transform into Orange Pearl Voice like Sara.
- Seira means "Holy and Good".
- Like Sara, Seira stands for the color orange of the rainbow.
- She is the youngest mermaid.