Less than an hour away from Tokyo by shinkansen (bullet train), Atami is home to hot springs, ryokan (traditional Japanese inns), museums and more. For me, one of the biggest draws is the Atami Sea Fireworks Festival, which occurs several times throughout the year (mostly in the warmer months).
What makes Atami special is that, despite its popularity, it’s not overly crowded. That means you get to enjoy topclass fireworks without the overwhelming deluge of spectators (particularly prominent in places like Tokyo and Yokohama), which can definitely take away from the experience.
Atami: https://www.japan-guide.com/e/e6317.html
Google Maps: https://maps.app.goo.gl/5eKVpwrVj1UFajcZ6