This is a guide for the easy way to get 100% of the achievements while doing something else on your computer or watching something else on TV or streaming.
At the main menu, click on the Systembutton. On the first page under the Skip Mode section, click on All.
Under both Auto Advance Speed and Text Speed sections, set the circle to max (all the way to the right).
Under BGM, SFX, and Voice sections, click on the Off button.
Click on the OK button to save your settings. Your screen should look similar to this.
Start the game and once the first dialog comes on screen, click on the Auto button. Enjoy!