Complex sentence: Yata ("first appearance": chapter 102) is a young swordsman seen in the meeting headed by Laymia, who suggests then executing Graffel and Hecatos-even though Graffel is his brother-for attacking Oga without an express order to do so.
Split into simpler sentences: Yata ("first appearance": chapter 102) is a young swordsman seen in the meeting headed by Laymia. In the occasion he proposed executing Graffel and Hecatos-even though Graffel is his brother-for attacking Oga without an express order to do so.