Tsumasaki ni Kourozu

From MangaUpdates:

1-3. Tsumasaki ni Kourozu
Iwai Arata was recommended by his professor to work part-time under a rather eccentric mycologist, Murota. The mycologist seemed hard to approach at first. But slowly as he got used to Iwai's presence, he became friendlier in his own way, showing Iwai a whole new world and giving him guidance with life. Though every day was fun and exciting, a sense of unease began to creep into Iwai's heart (from Echochi Scans)

4. Lingering Light
   Tsumasaki ni Kourozu - Extra

5. A Fish's Warmth
   Hirotaka has a secret. When people fall asleep, he sees fishes swimming out of their bodies, wandering and playing, and going back when they awaken. But, the deeper one's secret is, the more solitary he becomes.

6. Excursion at Midnight
   A Fish's Warmth - Extra

7. August, End of Summer
   When Haruhiko's grandfather dies, he stays behind in the old house for the memorial service. Left with regrets of lost time, a mysterious boy, and forty nine days in the countryside, Haruhiko finds himself accepting the oddities and discovering a beautiful place.

8. The Coming of Summer
   August, End of Summer - Extra