Four sisters are all involved with the medical field. Sora inherits a medical clinic in Shinjuku from her father, while Umi is a doctor researching gene therapy. Riku's husband owns a large hospital, and Mimi is a trainee doctor dreaming of becoming famous. The four sisters are shocked to meet an unknown half-sister, Hiyo, from Hokkaido.

• Atsuko Asano
• Maki Goto
• Misa Uehara
• Rei Kikukawa
• Kumiko Okae
• Keiko Kishi
• Ryunosuke Kamiki