Personal Notes (not spoiler free!)

[ik3men]

Background

• Lives with just his mother and little siblings at home, they are poor.
• Reason for being put in Class E was going against the school rule that no student should have employment on the side.
• The reason he works is that he really needs the money, with his mother's poorer health and also his own and his siblings' tutions.
• He wants to become a businessman when he grows up, one who does things fairly.
• Maehara is his best and childhood friend.

Class and Skills

• Best of the class in knives, directly after Chiba and Hayami in marksmanship.
• Works best partnered up with Maehara.
• Able to unite Class E as a group, Karasuma considers his leadership important in carrying out plans.
• Noted to have excellent kinetic vision, as well as nerves of steel when following a solid plan.
• In inquiries to teachers, very consistently the one to speak up. He serves as leader in delegating tasks for his classmates also.
• Isogai is among the division of the class that proactively participates in group assassination efforts.
• He plays tennis, though it is likely he hasn't had the spare time to for a long time.
• Top cook among the boys after Muramatsu.

Trivia

• The other two handsome boys of Class E are considered to be Karma and Maehara, but unlike them Isogai isn't "dangerous" (in this case being mischievous or a womanizer). 
• Even with cheap clothes, he has a good fashion sense and it doesn't look obvious. Probably fashion conscious.
• He regularly receives love letters even from those from the main building. Regardless of age, he charms those older than him too at work.
• Because he doesn't have very much, he gets excited about leftovers and free items.
• Might be ambidextrous, he has been seen writing both with his left and with his right in the manga. Classmates have switched knives (likely as part of training), but not writing hands.
• Folds toilet rolls' edges into a triangle shape out of habit.