Yuri Touhou Doujin: Chibirei!

Touhou Doujin: Chibirei! (ADULT/LOLI)
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By choice or by accident, Marisa manages to buy a strange and mediocre tasting tea from the market that chibi-fies all who drink it. Marisa and Reimu drink said tea, and after some angry looks from Reimu, Marisa decides to take advantage of the situation.

Circle:
「MeltdoWN COMet」

Original Title:
「ちびれい！」Chibirei!

RAW Source:
4chan anon/Unknown