Ninja Academy is the Specialty Building for the Ninja Monkey. It costs 
750 to purchase its first upgrade and it also increases the cost of Sniper Monkeys by 5%. This Specialty Building was added in an update to Bloons TD 5 on 21st June, 2012.
Upgrades
- Initial cost is
750 - Second upgrade costs 750
- Third upgrade costs 1750 (in the Mobile version it costs 750 and it makes shurikens last longer instead of having the Shadow Double Ability)
- (Bloons TD5 Mobile only) Fourth upgrade costs 1750, adds Shadow Double Ability.
Tips
Shadow Double Ability in use.
This appears a good strategy with use of the Ninja Academy.
This building can be very useful if Ninja Monkeys were one of the towers available in a game and with the shadow ninja on its side it can help support, although it may mess up your strategy if the player were trying to get Sniper Monkeys, as snipers can be a little expensive when reaching later upgrades. The shadow ninja appears at a random spot within the Ninja Monkey's range, and has the same upgrades as the Ninja Monkey using the ability. For example, a 0/0 Ninja Monkey will create a 0/0 shadow, while a 4/2 Ninja Monkey will create a 4-2 shadow. If used in masses, this can double the firepower (works well with Bloonjitsu Ninja Monkeys).
Trivia
- This is currently the only Specialty Building which adds a Special Ability to the tower, not counting the iOS Bombing Range & Super Monkey Lair.
- It is possible to have a Ninja Monkey with two different abilities at the same time, as long as this building's third upgrade is purchased and activated along with a Sabotage Supply Lines Ninja Monkey.
- If you sell the Ninja Monkey while the special ability is still in use, the shadow will stay until the ability is finished.
- If you have a Sabotage Supply Lines Ninja Monkey and you use the Shadow Double ability on it, you will not get another Sabotage Supply Lines ability.
- It is possible to click on the shadow monkey and it will show you a pop count. However, it will reset when the ability ends.
- The Ninja's Shadow Double ability is possibly a reference to the Shadow Clone Technique in the Naruto manga/anime.
- Increasing the cost of Sniper Monkeys can actually be a disadvantage because in the higher rounds people plan for a lot of Cripple MOABs. However, some people like to get Sabotage Supply Lines to slow down blimps and this lowers the cost of Ninja Monkeys (if you have tier I) so it's both good and bad.
- As well as this, Supply Drop Snipers may be worth more than other money-generating towers in the later rounds, which may hinder the player's ability to buy them.