My Friend's Little Sister Has It In for Me! Volume 3 by mikawaghost

Summer vacation. For any high schooler, a time to let loose and have some fun! But for unfortunate Akiteru, it just means stress, stress, and even more stress! As if his fake relationship with Mashiro wasn’t enough, Sumire’s dropped a tremendous bombshell on him. Iroha’s back in force with a teasing vengeance, and now Midori’s acting mighty suspect too. Will Akiteru make it through the summer with his sanity intact? Or will the complex web of relationships finally spell his doom?