Nanami Vol. 3 the Invisible Kingdom

The Gerfauts' schemes have born fruit. Siobhán drank the blood of Brigga the Witch, and evil has taken hold of her. Once a wise and generous ruler, she has become merciless, and is entirely devoted to Lady Gerfaut's son, whom she soon marries. Her own mother, Lady O'Mara, isn't invited to the wedding, and Séamus, her protector, is powerless to help. The last glimmer of hope lies with Kyle of Klanach and his unwavering love and loyalty...