In Onmyoji, there is a special type of shikigami Daruma that act as Enhancers for other Shikigamis. There are 4 different types of Darumas in the game: Black, White, Red, and Blue.
Most common used to feed others darumas
Best one after you feed them red darumas it gets more exp, and you can feed white with them
Used to upgrade shiki
Rare one when you feed shiki with black daruma it gains ability level up
Used to upgrade shiki
Most rare daruma, and hardest to obtain, when you feed shiki with black daruma it gains grade 6 and also 8 ability level up's, also this daruma not will be destroyed, but you can use it only 1 time per year

1. Take blue daruma and feed her with one red daruma
2. Blue daruma become level 8
3. Feed any shiki with this lvl 8 blue daruma and it becomes lvl 20
4. Upgrade lvl 20 shiki to grade 3

1. Take blue daruma and feed her with two(2) red darumas
2. Blue daruma become level 10
3. Feed white daruma with this lvl 10 blue daruma and it becomes lvl 20
4. Upgrade lvl 20 white daruma to grade 3, it level become 24
5. Feed lvl 24 white daruma 2 N shiki what you don't need, it level become 25
6. Upgrade lvl 25 white daruma

1. Take blue daruma and feed her with two(2) red darumas
2. Blue daruma become level 10
3. Feed white daruma with this lvl 10 blue daruma and it becomes lvl 20
4. Upgrade lvl 20 white daruma to grade 3, it level become 24
5. Take blue daruma and feed her with three(3) red darumas
6. Blue daruma become level 11
7. Feed lvl 24 white daruma with lvl 11 blue daruma, it level become 25
8. Upgrade lvl 25 white daruma to grade 4, it level become 30
9. Upgrade lvl 30 white daruma

Now with all darumas what you farmed just use to lvl up you main shiki to Grade 6

If you has any problems you can watch this video