Ch.1: Ameiro Paradox, Sugar Code, Ikasama Memori, Heart no Kakurega, Doushiyoumo Nai Keredo
Ch.2-3: Ameiro Paradox (already included there)
Ch.4: Tight Rope
Ch.5-6: Doushiyoumo Nai Keredo (ch.5 is already included there as vol2ch9.8)
read ch.6 first before reading Natsume Isaku Zenshuu ch38-39
or just binge read the author's works
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Vol.1 Ch.6, Ch.17: Dash (1st couple found in ch1-3, extra in 6)
Vol.2 Ch.18: Dash (2nd couple found in ch.4-6)
Ch.19: No Color (all chaps)
Vol2 ch31-32 is already included in Doushiyoumo Nai Keredo
Vol2 ch36-37: Doushiyoumo Nai Keredo (2nd couple found in vol2 ch7-9.2)
Vol2 ch38-39: Doushiyoumo Nai Keredo (1st couple found in vol1ch1 to vol2ch6.1, vol2 ch9.3-10.1)
In short, you should have read first Dash and No Color to understand vol1, and Doushiyoumo Nai Keredo for vol.2 (author makes crossovers with other works though)
that student looks worthy of being lead in a spinoff