Recommended itinerary: 14 days Tokyo → Kyoto → Osaka
D1-4: Tokyo (Shibuya, Asakusa, Shinjuku, day-trip Kamakura or Nikko) D5: Hakone (onsen, Mt Fuji view if clear) D6-9: Kyoto (Kinkaku-ji, Fushimi Inari, Arashiyama, day-trip Nara) D10: Hiroshima + Miyajima (A-Bomb Dome, floating torii) D11-12: Osaka (Dotonbori, Castle, Shinsekai) D13-14: back to Tokyo (Ginza, Harajuku, teamLab)
Covers the 3 major poles stress-free. Add 3 days for Hokkaido in winter or Okinawa in summer.