The Seven Deadly Sins series is a series of songs made by mothy. The series currently has 6 songs released and 1 songs planned. The Seven Deadly Sins, also known as Capital Vices or Cardinal Sins are used since early Christian times to instruct the morality of humanity. Minor sins "Venial Sins" can be forgiven through sacraments while "Cardinal Sins" would lead one to eternal damnation if not absolved through Penance or perfect contrition.
The Seven Deadly Sins have progressively changed throughout the years, but there is a general agreement with the current seven and their Latin names. Pride(Superbia), Gluttony(Gula), Envy(Invidia), Lust(Luxuria), Greed(Avaritia), Sloth(Acedia) and Wrath(Ira).
See also, The Original Sin
It seems that after collecting the Seven Deadly Sins together, something will happen. Currently it is not known what will happen but there are 3 people who wants to collect them. Elluka Clocktower from "Chrono Story" is on a quest to collect and cleanse the Seven Deadly Sins. The evil syndicate "Perre Noel" keeps beating her to them. Galleria Marlon/the collector wishes to collect the seven deadly sins together to make his wish come true.
The fourth song in the "Clockwork Lullaby" series, "Heartbeat Clocktower" has assigned a deadly sin to 7 Vocaloids before greed, sloth and wrath came out. The Kaito in Heartbeat Clocktower is later revealed to be the same Kaito in "Judgement of Corruption" = Galleria Marlon/the collector.
Songs in the series: