Vintage Japanese Hand-Painted Porcelain Teapot & Sugar Bowl Set – Satsuma-Style

Add an exquisite touch of elegance to your collection with this vibrant hand-painted Japanese porcelain teapot
The three blue characters on the base look like a workshop/studio name rather than an imperial reign mark. My best reading of the characters is 幸士堂 (pronounced Kōshi-dō or Xìng Shì Táng), which would be a maker’s or shop name — not a Kangxi/Qianlong imperial mark. I’m not 100% certain on the exact characters because the brushwork is stylized, but it’s definitely a shop/artist signature style rather than a reign mark.
How old is it?
Based on the shape, palette and decoration (very fine polychrome enamels, lots of raised/gilded dotting and detailed figure scenes, pastel ground colors) this is characteristic of Japanese export ware in the Satsuma / Kutani style rather than older Chinese imperial ware. My estimate:
Most likely: late 19th century → early 20th century (roughly c. 1890s–1930s) — the big export period for pieces like this (often sold as “Satsuma” or “Nippon” ware).