Project A-Ko was intended to be a sequel to Cream Lemon, one of the first hentai anime made. However, it was retooled into a parodic anime at the last minute and released as a double feature with Tabidachi: Ami Shuushou, the forgotten non-pornographic adaptation of Cream Lemon.
Tabidachi: Ami Shuushou truly is not that bad, but not that good either. The 80s animation, as usual, is a visual treat, and the cool J-pop soundtrack is nice, if a bit generic, but the positives end there. The plot is unimpressive and borderline offensive, which one would expect from an adaptation of a porno. This movie includes incest, an obvious sign of its pornographic origins, and other garden-variety pervertedness, which makes it an uncomfortable watch. Seriously, the plot portrays the continuing of the incestuous relationship as positive and happy. If that doesn't build up the yikes factor, I don't know what does.
I watched this because I was interested in its relation to Project A-Ko, and as someone who enjoyed Project A-Ko, I can say that Tabidachi: Ami Shuushou adds nothing to the experience and was largely forgotten for a good reason.