Hi. You can't ware a swimming costume in the hot springs.

Hi! According to the Japanese official website, there is a free shuttle bus service available from Odawara Station West Exit to the hotel everyday at 2pm, but you need to reserve a seat in that shuttle until the day before at 3pm. To reserve, you need to call the hotel at 0460-83-5111. When you leave the hotel you can also reserve a seat on a free shuttle bus that will take you either to the nearest bus stop or Odawara Station. If you're not taking the shuttle bus from Odawara Station, you may take a taxi from Hakone Yumoto Station (about 25 minutes, around ¥5,000) or take a Izu Hakone bus and get off at Ashi no yu bus stop. But if you are afraid of getting lost I do not recommend taking the bus. The reason is that when I went there, even though we were 3 girls used to life in Japan and fluent in Japanese, we missed the bus stop as it was in the middle of nowhere and announced very briefly on the bus. We eventually found Ashi no yu bus stop but we were not too sure where to go (there's a signal but it really looks like there's nothing around there) so we called the hotel and they sent a shuttle to come take us. On the website they say you can walk to the hotel from the bus stop, but it seemed quite a long walk to us, so we were glad we had called to request a shuttle bus. I hope it helps answer your question. Have a very nice trip!