By a journey to Japan on 1 to 5 months recommend protection against the following infections:
Diphtheria Diphtheria is a serious throat infection, which infects from person-to-person through the air. The vaccination should be less than 10 years old otherwise a booster is needed. Read more about diphteria here.
Hepatitis A (infectious hepatitis) Infectious hepatitis infects through contaminated food and water. Vaccination consists of two injections about 12 months apart, which protects for up to 25 years. The first vaccination protects for 12 months. Read more about hepatitis A here. The hepatitis A vaccine can be combined with the vaccine against hepatitis B
Tetanus Tetanus is a complication to wounds contaminated by soil. If there has been a vaccination within the past 10 years it is not necessary to give a booster in case of wounds and accidents. Tetanus vaccinations are usually given in combination with diphtheria vaccine. If you are previously vaccinated, the vaccine can be given right up to departure.
Japanese encephalitis is caused by a virus spread by mosquitoes. Vaccination consists of 3 injections with 2 weeks apart and protects for up to 2 years. Vaccination should start 4 weeks before departure. Travellers, whose visits are restricted to major urban areas, are at lower risk for acquiring JE and generally should not be advised to be vaccinated. Read more about japanese encephalitis here.