It was very quickly proven to not be ok after about thirty minutes. The sun was shining, if it actually was a sun, Kat wasn't certain of that part, but the light and heat from the maybe sun, was shining directly on the pair and Kamiko wasn't having a good time of it. To compensate, Kamiko was burning demonic energy to help cool herself down a little and Kat was starting to notice.
This is because when she looked over at Kamiko the faintest traces of pink smoke could be seen. Most of it was hidden under her outfit and concentrated around her core body but it wasn't sustainable long term and Kat managed to catch glimpses of it leaking out of Kamiko's sleeves.