Although there are two fountainheads and cold sulfur springs gush naturally (many onsens in Japan are drilled and pumped up), amount of the gushing is so limited.
There is also a small indoor bath.
One is only 2.5 liter per minute and the other is 5.8 liter, not enough for filling the baths. Therefore the sulfur spring was water added, heated, filtered, circulated (the water in the bath is reused again and again!) and chlorinated. No wonder I couldn't feel original character of the spring water at all.
The biggest problem was too much chlorination. The open-air bath smelled like an over crowded swimming pool at mid summer. I saw many visitors made faces and complained. The small indoor bath (see above photo) was bit better.
Location and atmosphere is very nice, and a man working there (maybe a manager) is a friendly, very nice person. If you just want to see and experience a Japanese onsen, I think you can enjoy without disappointment, but this isn't the place for soak addicts like me.
Not all onsens in Japan are recommendable, and I should admit unrecommendable onsens are increasing rapidly.
They accept day visit from 10:00 AM to 9:00 PM (until 8:00 PM in winter), charging ¥1100. Ladies' baths and men's baths are separated. If you pay ¥2500, indoor baths and sauna at main building are also available, including towels and Yukata rental. Overnight stay with dinner and breakfast starts from JPY 15,750 per head.
A freee shuttle bus meets every incoming train at the Kurama Station. Or you can walk to the onsen in 15-20 minutes. Eizan Densha from Demachiyanagi Station at central Kyoto takes you to Kurama in about 30 minutes.
Kurama Onsen （くらま温泉）
Kurama Station （鞍馬駅）
Eizan Densha （叡山電車）
Demachiyanagi Station （出町柳駅）