Usotsuki! Gokuo-kun

The world is overflowing with them: fibs, falsehoods, lies... Surely you, too, Reader, have told a lie at least once in your life, with your heart beating fast. This is a story about dealing with those lies. The protagonist, Gokuou, is a master liar, who loves both lying and exposing other people's lies. Together with his strange pet, Nekokarasu, he starts to expose the ocean of lies in his new school. Fighting lies with lies, all Gokuou needs is the power of the "tongue." "What exactly does that mean?" you ask? Have a look and find out!

(Source: Shogakukan, translated)

Note: Usotsuki! Gokuou-kun won the 61st Shogakukan Manga Award in the children's category in 2015.