Shikoku 3days 2nights

I would like to visit Shikoku im my trip.
I'll get to Shikoku from Kyushu, currently by JR trains.

I would like to see Ritsurin koen in Takamatsu, Naruto whirlpools and Kotohira kompira-san and kabuki.

Is there anything more to see in Shikoku around those area?

Takamatsu has a few more, mildly interesting sights:
http://www.japan-guide.com/e/e5400.html

But much more than that does not fit into a 2-night stay, anyways.

You can take a short cruise from Kojima which passes beneath the Seto Ohashi twice. It is a pleasant way to see the bridge and pass a couple of hours.

Naruto and Tokushima in general is underwhelming. I would suggest one day in Takamatsu (Ritsurin Park in the morning and Kotohira Shrine in the afternoon with an evening stroll through the shotengai and dinner in Kitahama Alley)

For your second day I STRONGLY recommend shifting your focus to Matsuyama -- Dogo onsen and Matsuyama castle are both lovely and the city has quite a lot more going for it in atmosphere and history than Tokushima (which is nigh impossible to see much of without a car).

~ from a local

...If you are even mildly interested in art, architecture, or design, or if you would like to see a small island village, I cannot recommend highly enough to go to Naoshima (ferry from Takamatsu).

Benesse House, http://www.naoshima-is.co.jp/english/index.html , the Chichu Art Museum, and the Art Houses project are so good that they would be the first place I would want to revisit in Japan (after 4 trips, going to all the main islands, etc. My wife shares my view on Naoshima.)

It's expensive to stay at Benesse, but I'd say it's definitely worth it, and would happily pass up indulging in lots of my favourite treats at home in order to save to stay there again. If you do, the most wonderfull thing is to have dinner in the museum. All the visitors go home. Most of the other guests at Benesse are eating in the restaurant in the hotel, but you (and about 10 other tables, iirc, have the whole museum to yourself for a night and it is magical.

Anyway, you can probably guess that I could go on about the place forever.

Ritsurin Koen is pretty good. If I were to rank the ones I've been to, I'd put the Adachi or Kenrokuen ahead of it, but they're all three very good in my book.

There's not much else in Takamatsu town (that we found, anyway), but it's easy to navigate and there are some good small bars and restaurants (the local noodles are worth a try), and I suppose it will be your base for the whirlpools.

Dogo is pretty, and if you enjoy onsens then it would be a shame to miss at least a flying visit to kame no yu (I think that's what the famous old bath house is called). We just did that, and then spent the rest of our afternoon and evening there eating and bathing in a lovely ryokan.

The train ride from Matsumoto to Takamatsu gives some good views of the coast at points.

Hope you have a lovely time

If you get over to Matsuyama to check out the hot springs and castle as suggested above, you could take a ferry from Matsuyama to Oita in Kyushu and take a short train ride up to Beppu. There are also ferries from Matsuyama to Hiroshima for an Inland Sea cruise.

A little known but fun diversion is to participate in the Sakagura Rally. 88 participating Sake breweries have a tasting area where you can, for a small voluntary donation, sample their sake. If you get all of the stamps from a single prefecture, you can receive a certificate, but if you are able to get all 88 you get a special certificate. As of today, 9 people have completed the rally. In fact, you have one year to visit all 88. I have not found an english translated site, but the Japanese site is www.a-kiss.net/sake88//.