Although this ‘Planetarian: Snow Globe’ is labeled as a prequel of ‘Planetarian: Hoshi no Yume’, there is no actual enforced watching sequence. However, it is recommended to watch this prequel first. If you have watched the sequels, it is still worth watching this anime. This OVA shows some past stories of Yumemi-chan and other Planetarium staff. Its plot is insipid, but comfortable and satisfying. It granted an experience of ordinary simple tiny happiness. This happy style (probably) will be liked by everyone. It improved the reasonability of the characters’ later behavior significantly. It will be easier to understand the characters’ later activities, if this prequel is firstlywatched.