Maseki Gurume: Mamono no Chikara o Tabeta Ore wa Saikyou! summary:

In this world, It's only me who can get stronger by eating Magic Stones! <br><br>At one point, I received an offer to have a smooth life reincarnation from the Goddess-sama... But the skill I got as a prize is Toxins Decomposition EX. Ugh, what a plain skill! Its so pitiful that even my own family makes fun of me... <br>However, one day I realized that because of this skills effect, I can eat and gain power from Magic Stones! I've also been notified that I'm the prince from a neighboring country!? What awaits me in the castle are days of experimenting with Magic Stones and training, the perfect environment for me to become the strongest man there is... <br>And to top it off, I received the Magic Stone of Dullahan! <br>The story of a boy on the path to become a King while being chased by an assertive fiancee and Female Knights starts here!