The imessage (그린) - 카카오톡 테마 is a free Android app developed by W2D_what2do. It is available to download from the Google Play Store and is categorized under Lifestyle. The theme is exclusively designed for KakaoTalk users who have version 8.0 or later installed on their devices.

To apply the theme, users need to download the imessage (그린) - 카카오톡 테마 app and launch it. Once launched, they need to click the apply button to set the theme. The app also provides a blog link to the creator's blog and an email address for theme inquiries and reporting errors. However, it is important to note that the app does not provide any additional features or functionalities, as it is just a theme for KakaoTalk.

Overall, imessage (그린) - 카카오톡 테마 is a simple and easy-to-use app that provides an aesthetically pleasing theme for KakaoTalk users. However, it is limited to only those who have version 8.0 or later installed.