1. From Narita Airport, please refer to the following train routes to go until Odawara Station. Fare is covered by the JR Pass. Train schedule is for reference only.
2. From Odawara Station, you may buy the Hakone Free pass (http://www.japan-guide.com/e/e2358_008.html) which covers most if not all transportation need within Hakone. It costs 3900 yen and is valid for 2 days.
Then follow the below train routes until Gora Station. Fare is covered by the Hakone Free pass. Train schedule is for reference only.
3. Take the cable car from Gora station to Koenkami station (only 2 stops away, fare covered by Hakone Free Pass) then follow the follow directions here (http://www.japanbooking.info/ryokan/kiritani-hakoneso/location#walking_direction) to reach Ryokan Kiritani Hakoneso.