Budapest Japan Day in Budapest
Multiple similarly named Japan-themed cultural days run in Budapest each spring, most plausibly the Hopp Ferenc Museum's Budapesti Japán Napok, alongside separately organized events including Japán Nap Kizuna, Japánkerti Nap at the Zugló Japanese Garden, and the summer Natsu Matsuri, making a single confident identification difficult.
Budapest hosts more than one Japan-themed cultural day, and this listing most likely points to Budapesti Japán Napok, a program run by the Hopp Ferenc Museum of Asiatic Arts together with the Hungarian-Japanese Friendship Society, though overlapping names attached to similar events around the city make a single confident identification difficult.