LOCKDOWN ZONE: LEVEL X

Ryoka is awakened by flurry of text messages from her mother! Panicked and rushed, Mom is clearly concerned for Ryoka's safety, but she is not too keen on letting her daughter know why. Her reasoning being that nothing could really properly describe what is happening! The world might be ending! And there might be a massive new life-form on the roof of their apartment building! (Source: Denpa) — Description from AniList community (anilist.co).