Kemurikusa (2018)
Japanese title: ケムリクサ
Type: ONA
Source: Original
Episodes: 7
Status: Finished Airing
Aired: Aug 31, 2018 to Apr 6, 2019
Duration: 1 min per ep
Rating: G - All Ages
Studios: Yaoyorozu
Genres: Fantasy, Sci-Fi

Prequel vignettes to the Kemurikusa TV series released on Tatsuki's official Twitter. They have an irregular episode count as follows: ep 0 (in actuality, it is unnumbered), 0.5, 0.6, 0.7, 0.8, 0.9. 

After the Kumurikusa TV series finished airing, Tatsuki released another vignette the following week numbered ep 12.1 both on his Twitter account and official YouTube channel for a grand total of 7 web shorts tied directly to the TV series.