The Summon is available after completing a quest at level 21. The first summon you will receive is the one-tail Shukaku. You can raise it's level by boosting with either silver, gold / coupons, or channeling scrolls. If you choose advanced boost, it will automatically use your currency in this order: channeling scrolls -> coupons -> gold.
Each boost with silver costs 15,000, with a chance of an S Crit for 10x EXP. Each boost with gold / coupon / scroll costs 10 gold or coupons, or one scroll, with a chance of S Crit for 10x EXP, and L Crit that directly boosts 1 soul.
The summoned beast's statistic boosts are only active during Arena, Konoha Conquest, Konoha Defense, Suppress Beasts, and Rebeller's Attack. They do not affect Realm, Trials, Top Kages nor normal combat stages.
You can choose to display your summoned beast, or hide it. You should always display it. The wording ingame sounds as though you keep all statistic boosts even when your beast is hidden, but this is not the case. What you can do, is revert the look of your beast to a previous version. If you have a sanbi (three-tail) and do not like the model, you can make it look like a nibi (two-tail).
Disclaimer: the stats / boosts on the summons shown in the picture gallery are representative of a high level summon being transformed to look like a previous version. You will not have these same statistic boosts upon first receiving these summons.
Stats - Force / Chakra / Speed / Power Edit
Refine (Summoned Beast)Edit
Available at level 72, you can refine your summoned beast. This is a system that utilizes solely coupons / gold, and does not use silver.You must level up each of the six stats before the game will allow you to continue to raise others. You have only the option to refine or refine all. Each practice costs 10 gold, or 'soul refining pills' (probably like channeling scrolls, but not seen ingame yet), and you get 10 EXP with a chance for an S Crit for 10x EXP, and L Crit that directly increases 1 level.