ICOCA can be used not only in Kyoto but also everywhere, and can be used not only for transportation but also for all kinds of shopping and dining.
On the other hand, if limited to Kyoto alone, and only the subway or bus, there is even more convenient ticket. It's Subway & Bus 1-Day Pass.
You can ride the subway or bus as many times as you like on the day you buy it. The price is 1,100 yen for adults and 550 yen for children, and you can buy it at the bus information desk or at the subway station window. Vending machine for it is also available.
You can buy it even from the driver on the bus. In this case, be careful because it may be sold out.
Only when you get on the bus for the first time with this ticket, insert the 1-day pass into the card slot in the fare box. The date is printed on the back. From the second ride, please show the driver the date printed on the back. Inserting is not needed.
When getting on and off the subway, please pass your 1-day ticket through the outlet of the automatic ticket gate. Only the first ride, date will be printed on it. From the next time onwards, it is OK if you put it in the ticket gate normally. Don't forget to take the 1-day pass that comes out.
It is a must-use on the day when you want to visit many places in Kyoto.
In addition, if you have this ticket, you can receive various special benefits at shrines and temples, cultural facilities, restaurants, baggage storage, etc. For example, the entrance fee to Nijo Castle is discounted by 100 yen.