There are over 1,000 games tagged "Visual Novel" for sale on Steam until August 14th.

Here are some notable dual-language titles:

• Muv-Luv & Muv-Luv Alternative are more than 50% off. Both games are dual-language.
• Steins;Gate and Steins;Gate 0 are 60% off.
• Aokana is 50% off.
• The House in Fata Morgana is 35% off.

Localization-only releases (i.e. they don't include the original Japanese script):

• Wonderful Everyday (AKA Subahibi) is 40% off. Remember to get the patch for the other 90% of the game afterward though, as the publisher provides it separately to the Steam purchase.
• Baldr Sky is 60% off.
• CLANNAD is 70% off.

There are plenty of other great games here, too. It's a huge sale. I recommend Muv-Luv.