The Clockwork Lullaby (ぜんまい仕掛けの子守唄) series is currently made out of 6 songs created by mothy. Some other people may translate it as the Clockwork's Lullaby or Spring-worked Lullaby.
The songs in this series doesn't have a connection though story and any song that has "Ru ri ra"/"Lu li la" in them is considered to be in the series. Story wise, they don't connect but most of the songs have connections with mothy's main story.
The second song "The Girl of the Miniature Garden" is directly related to "Judgement of Corruption" as the "daughter" and "father" in both songs are the same people. "Heartbeat Clocktower" should take place right after both of them go to hell.
"Re_birthday" was often debated among fans if it's included into the Story of Evil. Although it is officially in the "Clockwork Lullaby" series, if "Re_Birthday" is taken in direct canon of the Story of EVIL, it tells the story about the servant finding a way to revive himself.
"Heartbeat Clocktower" was only viewable at mothy's Piapro page. The song was then included in his album "prelude to forest". Then only did he post it up on his Nico account. (F.V. = Forest Version) This song also assigns a Deadly Sin to each Vocaloid when the Kagamines are singing "Lu li la"
Songs in the series: