Collection of extras and previously uncollected chapters:

Ch. 7.5: Hi Kya to Otaku no Eiga Date (陽キャとオタクの映画デート)
Ch. 18.5: Shuugakuryokou Ichi Nichime, Yoru (修学旅行１日目　夜)
Extra: Shuugakuryokou Ichi Nichime, Datsuisho Nite (修学旅行１日目　脱衣所にて)
Extra: Toaru Ame no Hi no Futari (とある雨の日のふたり)
Extra: Sonogo no Futari: Izumi to Iroha (その後のふたり～泉といろは～)
Extra: Sonogo no Futari Sotsugyou Kouhen (その後のふたり～卒業後編～)
Illustrations Gallery

(Source: Takeshobo)