Shall I briefly explain their origins:

Cycle 1 was made of shadows, and light was shining. This light was Mariko, the only character notable in this cycle.

Cycle 2 was made of light, yet shadow screamed. This shadow was the beginning, and it purged through all the light rained through Mariko.

Mariko's soul divided and created Joseph, one of two Perfect Middles. The other notable character's souls either are mariko recrystallizarions to a minor level ( Imperfect Middle ) or are extraplanar or shadow souls.

Cycle 3 functioned on a much similar way to cycle 2, however souls are more refined. The second Perfect Middle is found here, Rose.

Cycle 4's characters are basically Valkyrie, an extraplanar soul and Purun, the Perfect End, a mix of Rose and Joseph, resulting in something resembling Mariko once more, but much more mature.