Best chapter, when Kyoya remembers his past with Tamaki. In the anime shows how Tamaki gathered all the members of the Club, but this chapter was more detailed. Kyoya does not stand a chance with Tamaki :D
Or maybe the best chapter is the last one, where Tamaki is confused about his father role. OMG he is hilarious. And so dense!
Although the extra chapter where the mangaka tells several "embarrassing" moments for Kyoya was also very funny.