Matsuyama is the largest city on the island of Shikoku, about 90 minutes by ferry and local train from Hiroshima and about 5 hours by train from Kyoto. As home to one of the oldest onsen bathhouses in the country, Matsuyama is popular with domestic tourists, but is hardly on the international tourist radar.

See & Do
For domestic tourists, Dogo Onsen, one of the oldest in the country, is the big draw. I personally love onsen, and had a great time here! I wouldn’t recommend this for your first onsen visit as it is very traditional: there is a single large bath and no separate shower area. Patrons use small basins to scoop the onsen water out of the communal bath to wash their hair and body while squatting on the floor. For more on onsen etiquette, see this post.
Between Dogo Onsen station and the onsen itself, there is a long pedestrian shopping arcade filled with great restaurants and cafes. It is also possible to enjoy geisha entertainment here at Hanahimero tea house.

In the center of the city, Matsuyama Castle is one of only 12 original castles left in Japan. The castle was built in 1603 and has been a National Historic Site since 1952. You can walk (really a hike up several sets of very steep stairs) up to the castle, or take advantage of the convenient ropeway.
Once at the top, you can command sweeping views of the city and surrounding countryside. You can also enter the Main Tower of the castle. Please note that you will need to remove your shoes to enter the castle and that some of the stairs inside are quite steep and cramped.
If you’re visiting in the spring, Shiroyama Park next to the castle is a great place to see sakura, or cherry blossoms.

Near the castle, the Nibancho neighborhood is nice to walk around as well for the small traditional shops.
If you have a bit more time in the city (and possibly a set of wheels), 8 of the 88 temples of the Shikoku Pilgrimage are located in Matsuyama. More information on the Shikoku Pilgrimage can be found here.
Eat
While in Matsuyama, you should try some of the local specialties. These include oranges; over 30 varieties of citrus fruits are grown in Matsuyama, and many are made into other foods such as ice cream and jelly.
For dinner, seafood is a popular choice here. Sea bream rice uses fresh sea bream from the nearby Seto Inland Sea. Matsuhamayaki is Matsuyama’s take on the popular dish okonomiya. And Nabeyaki udon, unique to Matsuyama, is a well-cooked noodle in broth that is sweeter than what is found elsewhere in the country.
For dessert, try Matsuyama’s take on dango: the 3 balls of mochi here are flavored with matcha, egg, and adzuki beans. Taruto is shaped like a roll cake; the filling is a mix of sweet bean paste and local yuzu.
Getting There
While it is possible to get to Matsuyama by train, there are also a couple of more unique ways to arrive. From Hiroshima, there is a direct ferry to Matsuyama Port in Takahama (1h10m). From Takahama, you can take a local train to Matsuyama. If you like cycling, the Shimanami Kaido cycling route that crosses the islands of the Seto Inland Sea is an absolutely stunning way to get from Honshu to Shikoku. You can rent bikes at Onomichi and drop them off at the end of the day (about 70km in total) in Imabari. From Imabari, you can take the train to Matsuyama (35 minutes)