Tag : female Futanari (2 and 3rd), Yuri (1st part)
This is actually a multiwork series from author work in Pixiv webmanga. It's explained that Kaneko-kun (the MC) was actually a guy that can randomly change form. The first time he changed form he became a Shota and from there author somehow create a different version or timeline.
In this timeline, Kaneko-kun turned into a girl and his girlfriend can grow a dick (futanari).
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