Yep. This one and "Colle Muto" are marked not suitable under18 for contents of violence, death and western/horror themes related. It's not NSFW since they don't show nudity or sexual violence or stuff like that, but for the possibility to include themes like drugs, murder, blood, criminals, etc...

According to the webster dictionary https://www.merriam-webster.com/dictionary/NSFW NSFW is used to warn someone that a website, email attachment, etc., is not suitable for viewing at most places of employment. This games are suitables for being played in office in the launch pause, for example... than it is not NSFW in our opinion ^^