Hi ​@Shinichiro Yamaki, 

Welcome to Box Community, and we’d love to assist! 

To answer your question, yes it is possible to open a CSV file in Excel using Box Tools. Box Tools uses the default application installed on your computer to open and edit files stored in Box. For CSV files, if Microsoft Excel is set as the default program for that file type (including the “edit” verb association on Windows), then opening a CSV file with Box Tools will launch it in Excel.

You may need to ensure that the file type associations are correctly configured on your computer so that Box Tools opens CSV files with Excel rather than another program like Notepad. After editing, saving the file in Excel will save changes back to Box automatically as a new version.

Hope it helps, and please let us know if you have additional questions.