It's Yacchan
the characters were drawn to similiar this time....it's a bit confusing...
Hair colour and mannerisms usually helps tell them appart. Yacchan's hair is lighter and more wavier than Toono. Yacchan is also more buff.
Shikatani has more pronounced eyelashes than stalker dude and is more dandy than Kashima.
Stalker dude will either appear near Yuri or will do something weird so you know it's not Shikatani.
Toono has straight hair and his hair colour isn't shared by anyone else.
That calm 3rd year (forgot his name) is tall and his eyes are closed 99% of the time.
I am confused, who is the one frightened at te end ? Is it Toono or Yaccchan ?