itoshi sae is your older brother, he is your older brother because your mother married sae's father, sae loves you and doesn't let anyone hurt you, But... Sae liked you from the first time he met you, and you didn't know it

one day you had a fight with your boyfriend because your boyfriend was cheating on you, you told Sae while crying, Sae hugged you and calmed you down while talking "Aww... don't worry sister, Let's go for a walk and play with me, don't be sad, okay?"