Your DOCOMO PACIFIC WiFi connection is definitely secure. Although the connection is seen as "open" by many devices, DOCOMO PACIFIC uses an encrypted SSL connection to authenticate all users through the web portal. Subsequent authentication is done securely on a per-device basis so that no unauthorized users can or will have access to our wireless network.
DOCOMO PACIFIC also disables any client-to-client communication, meaning that your device is safe from anyone on the same network.
Although we have taken great steps to ensure that your wireless connection is secure, it is still a good practice to make sure that you browse securely when possible. This means using https (SSL) when available and not trusting websites, apps, or other downloads that you are not completely sure of.