Hello! It's great to hear that you are planning your journey across Hiroshima, Okayama, and Tottori in Japan. Here are some essential travel tips for you.

Best Time to Visit:
The best time to visit these cities is during the spring (March to May) when the cherry blossoms are blooming, or in the fall (September to November), when the leaves are changing color. The weather during these seasons is usually pleasant without extreme temperatures.

Route and Accessibility:
All these cities can be comfortably visited by the Shinkansen, Japan's well-connected bullet train system, or by domestic flights within Japan. Hiroshima is a major stop on the Tokaido/Sanyo Shinkansen line, while Okayama and Tottori can be accessed using JR lines. Local buses and trams are prevalent too.

Accommodation and Booking:
There's a wide range of accommodation options available in these cities, from upscale hotels to traditional Japanese inns (Ryokans). It's advisable to book in advance, particularly during the peak season to ensure good options. Websites like Booking.com and Expedia provide plenty of choices.

Clothing and Essentials:
Be sure to pack lightweight and breathable clothing for the summer months. For cooler seasons, layering is a good strategy. Carry an umbrella or a raincoat as rain showers can be unpredictable. Don't forget your essential toiletries and medical prescriptions.

Health and Safety:
Japan is generally a safe country with a low crime rate. However, it's always advisable to take basic precautions with your belongings. Check local forecasts for updates on typhoon warnings, especially during June to December, and plan accordingly.

Local Etiquette and Respect:
Respect for local customs is essential in Japan. For instance, it's considered polite to bow when greeting and take off your shoes before entering someone's home or certain traditional places. Maintain silence in public transports and avoid eating while walking.