Your specs looks fine (I assume you have a decent graphics card too). There is probably an error in the demo. I am currently traveling so I can not check myself. Will be back next week then I can sort this out.
In the meanwhile, you can either upload the log file somewhere (it is file ending in .log) and link it here or copy-paste its contents here - especially the last lines since that is where error message will be.
Open Windows Explorer and past this line in the address bar (the bar just above the panels showing your folders) and you should be auto-navigated to the location of the log file. %USERPROFILE%\AppData\LocalLow\jakai\tentikun\
or manually browse to: C:\Users\YOUR_USER_NAME\AppData\LocalLow\jakai\tentikun\