I have gotten the endings for all four characters, read the five omake, unlocked all the character profiles, etc. Visiting the secret place on weeks 1 and 5 only leads to the bad ending still. =/
Viewing post in There's no such thing as a harem comments
Maybe weeks 2-4 are the wrong places to go.
As indicated in the description column hint, the location for weeks 2-4 also needs to be correct.
There are strategy answers on my website below, and I have prepared an English version.
If you need them, please use them.
(Go "Game" and click "All route answers" in There's no such thing as a harem)
https://anomalyxxx.wixsite.com/anomaly