This is a fairly obscure traditional model. The only direct reference I found is from Alice Gray and Kunihiko Kasahara’s “The Magic of Origami” (1977), which contains a Bell which is “an adaptation of the traditional bell flower”, with a small picture of the original traditional model. There is also a possible indirect reference in the English translation of Toyoaki Kawai’s “Origami” (1970), which includes a similarly constructed pentagonal “broad bellflower” on the same page as a modulation of the traditional iris onto two triangles.
Stylistically, this is typical of 19th-century traditional Japanese origami; it is developed from a frog base, it is intrinsically three-dimensional, but it is still simple, memorable, and easy to fold. Furthermore, Alice Gray and Kunihiko Kasahara were very careful to attribute models properly in their book, so I think we can confirm this is a traditional model.