Offers courses to learn Japanese in the capital city of the country, Tokyo. The class is held in the business district.
Courses include 4 hrs/day or more in a classroom environment with no more than 20 students.
Accreditation: Instituto Cervantes
Academic credit: Yes, through Brookhaven College
Accommodation: Homestay or shared/private apartment.
Duration: 2 weeks or more
Prices: from $760 and up

Valiant Language School offers practical lessons centered on day-to-day situations to help students pick up a communicative conversational understanding of Japanese. Located at Valiant Management College in the Roppongi business district.
Courses: Group intensive, private, business, JLPT Test Prep
Lessons per week: 3 hours
Accreditation:  Not disclosed
Academic credit: Not disclosed
Accommodation: Private apartment, or hotel
Costs: ¥27,000 / week (or $259 USD)

HLI offers students a Japanese language immersion program in Tokyo. All ages are eligible for private language instruction in the teacher's home.
All teachers have a Bachelor's degree or a teaching certificate.
Lessons per week: 10 to 30 hours
Accreditation:  ABLS, UNOSEL, ALTO
Academic credit: No
Accommodation: Homestay
Costs: from $1,580 USD / week

Language Booking provides access to various Japanese programs created specifically for: high school and college students, adults, or language course with cultural activities.
Savings are greater when more weeks are booked and they offer a "best price guarantee"
Course locations: Tokyo, Sapporo, Fukuoka
Levels: Beginner, intermediate, advanced, proficient.
Duration: 1 week to 52 weeks
Class size: 5 to 14
Lessons per week: 10 to 30 hours
Options: Language with cultural activity.
Accreditation:  Yes, too many to list
Academic credit: ???
Accommodation: Host family, residence or flat.
Costs: from $132 per week

Provides access to language programs in multiple countries.
Course available in: Tokyo, Sapporo, Nagoya, Fukuoka, Gifu, Kyoto, Nagano, and Osaka.
More than 60 courses for fluency levels from basic, general, intermediate, through intensive. Class sizes are group, small group, and private lessons. Courses reserved for ages 12 to 55 years old.
Duration: 1 week to 52 weeks
Class size: 1 to 10 students
Lessons per week: 10 to 30 hours
Options: Language + culture.
Accreditation:  Yes, too many to list
Academic credit: Yes, for some schools
Accommodation: Host family, shared student housing or private apartment, hotel.
Costs: from $220 per 1 week.
( much less for 4 weeks or more. Example: $350 for 4 week course)