Obtained from Jacques Marty and labeled 'Suisen', but clearly not polyploid; no thick petals and no inhibited fertility. Might be the diploid form Eiga-no-Homare or a diploid Suisen sibling like Hitomebore.
Mark Nijland extensively used this azalea in his breeding, obtaining nice results.
Probably is 'Sato no Hikari', possibly 'Miyuki', based on the coding system, images and stock at the seller.
Breeding code: u