Shop
➥ The Shop is a place that sells various in-game items using in-game currency or real currency. I don't think there is more to explain here because it's so straight to the point~ This feature is not locked by any Ninja Rank, but you need to complete the beginner's tutorial when you first start the game.
Recommended
➥ In the Recommended section, it's only for P2P players (Pay-to-play) as the packs sold need real currency to buy.
➥ Frost Blaze Pack is the latest time-limited pack (Mid-February) that will last less than 2 weeks.
➥ Dragon Contract is one of the most valuable packs you can buy monthly if you're going to spend money in the game (With Battle Pass being second). A total of 3500 Jades can be obtained after buying it, but make sure to log in daily so you can claim the Jades.
➥ Once you reach Senior/ Elite/ Eminent/ Super/ Shadow Ninja Rank, a new pack will be unlocked permanently in the Shop. Of course, the higher your Ninja Rank is, the more valuable items will be included in the pack. It's a one-time offer but it is permanent (2000 days sounds permanent to me) so you have a long time to consider whether you want to buy it or not.
➥ The last pack in Recommended is Monthly Pass which will change monthly.
Skin
➥ There are 4 dynamic skins available in the Skin Shop and it's permanently available for you to purchase using real currency.
➥ Before buying, you can go to Ninja > Skin and click on the Preview Ninjutsu Special Effects to see the said Ninja in the outfit and fight a boss in a battle.
➥ After you purchase the outfit, you can still change the Special Effect from the default to the new one, still in the Ninja > Skin.
Special
➥ The Special section is the combination of using real currency and usage of Jades. The Weekly Offer will refresh once a week (Reset at 15:00 Every Sunday) so you can buy the pack you are interested in every week. Meanwhile, for the Daily Offer, it will refresh daily at 15:00. The most important item here is definitely the free Daily Gift of 5000 Coins that you can get every day.
➥ Ninja Development sells fragments of random Ninja and also random Stone Pack. You can wait for the daily reset for the characters to change and get the Fragment of the Ninja you want. But don't forget it requires Jades to buy the pack.
➥ The last two in Special are Weapon Enhancement and Relic Crafting. Both of them will be reset at 15:00 Every Sunday.
Mystery
➥ Mystery is the last section in Shop and it's the combination of Coins and Jade's usage. F2P players who have lots of Coins may want to buy the Bounty, Relic, Stone, and Hammer that can be bought with Coins for future investment. The items will be refreshed at 15:00 every day but you can refresh them manually by using 30 Jade a maximum of 10 times per day (Not recommended for F2P players).