During my grade school days in Japan, there was an extracurricular activity, called a “social studies field trip”, where I got to visit a local factory.
In recent years, more and more companies are actively accepting factory tours in order to create corporate fans, and field trips for adults are very popular. Such tours can easily be enjoyed, because they usually are free or cost only a few hundred yen.
I have primarily selected spots close to Tokyo.
Note that in some cases you must apply in advance, or there may be age restrictions or limits on the number of people in a group. Check with each site for details. Most websites are in Japanese only, but try to do the best you can.
Beer tastes significantly different depending on the country. Japanese beer is relatively easy to get used to for people from overseas.
Almost all beer factories allow beer tasting, so I recommend these tours for beer lovers.
KIRIN（Yokohama City, Kanagawa Prefecture）http://www.kirin.co.jp/entertainment/factory/yokohama/tour/
ASAHI（Minamiashigara City, Kanagawa Prefecture） https://www.asahibeer.co.jp/brewery/kanagawa/
SUNTORY（Fuchuu City, Tokyo）http://www.suntory.co.jp/factory/musashino/
SAPPORO（Funabashi City, Chiba Prefecture） http://www.sapporobeer.jp/brewery/chiba/
For Japanese sake, there is a huge warehouse called a sakagura (酒蔵) that you can tour.
SAWANOI （Oume City, Tokyo） http://www.sawanoi-sake.com/service/kengaku
KOYAMASHUZO (Kita Ward, Tokyo) http://www.koyamashuzo.co.jp/kura.html
ISHIKAWASHUZO（Fussa City, Tokyo） http://tamajiman.co.jp/tour/
You can also see how soy sauce, an integral part of Japanese cuisine, is made.
Yugeta Soy Sauce (Hidaka City, Saitama Prefecture) http://yugeta.com/oukoku/contents/kengaku.html
Kikkoman Soy Sauce (Noda City, Chiba Prefecture）http://www.kikkoman.co.jp/library/enjoys/factory/pdf/eigo.pdf(English site)
Automobiles and Motorcycles
You can see the history of Japanese cars and motorcycles, and famous cars from the past. These tours should be irresistible to car and motorcycle enthusiasts.
TOYOTA（Toyota City, Aichi Prefecture）http://www.toyota.co.jp/jp/about_toyota/facility/toyota_kaikan/index.html
NISSAN (Several plant tours exist) http://www.nissan-global.com/JP/PLANT/
HONDA (Several plant tours exist) http://www.honda.co.jp/kengaku/index.html
MAZDA (Hiroshima City, Hiroshima Prefecture）http://www.mazda.com/ja/about/museum/guide/
SUBARU (Oota City, Gunma Prefecture) https://www.subaru.co.jp/csr/factory-tour/
SUZUKI（Hamamatsu City, Shizuoka Prefecture）https://www.suzuki-rekishikan.jp/
KAWASAKI （Kobe City, Hyogo Prefecture）
https://www.kawasaki-motors.com/kaze/prev/kojo.html(Regular tours）(English site)
http://www.khi.co.jp/kawasakiworld/(Akashi City, Hyogo Prefecture）
(Kawasaki limits tours to motorcycle clubs only)
YAMAHA（Iwata City, Shizuoka Prefecture）http://global.yamaha-motor.com/jp/showroom/cp
The airplane hangars are incredibly impressive.
ＪＡＬ （Oota Ward, Tokyo）http://www.jal.co.jp/kengaku/tour/
ＡＮＡ （Oota Ward, Tokyo） http://www.ana.co.jp/cp/kengaku/index.html
You can even buy gifts and souvenirs. There’s even a place that offers all-you-can-eat ice cream for free!
glico (Kitamoto City, Saitama Prefecture) https://www.glico.com/jp/enjoy/experience/glicopiaeast
（Hokkaido, Tochigi Prefecture, Hiroshima Prefecture）http://www.calbee.co.jp/factory/
AKAGI (Honjoo City, Saitama Prefecture) http://www.akagi.com/factory/index.html
*This is the manufacturer of the popular Garigari Kun ice cream in Japan.
chateraise （Hokuto City, Yamanashi Prefecture）https://www.chateraise.co.jp/enjoy/02factory.php
unagipai（Hamamatsu City, Shizuoka Prefecture） http://www.unagipai-factory.jp/tour.php
shiroikoibito（Sapporo City, Hokkaido）http://www.shiroikoibitopark.jp/english/
royce (Chitose City, Hokkaido) http://www.royce.com/contents/english_rcw/(English site)
（Yokohama City, Kanagawa Prefecture） http://www.cupnoodles-museum.jp/english/index.html(English site)
You can make your own original cup ramen, including drawing a picture on the container and choosing the ingredients.
Yamato （Oota Ward, Tokyo）
You can tour the latest facilities of a Japanese distribution company that delivers luggage quickly and accurately.
Railway-Museum (Saitama City, Saitama Prefecture)
This is a museum, so it is a little bit different from a social studies field trip, but it is a very popular spot for those who like trains.