Combat/Battle Opening
Battle Opening Breakdown
Battle Opening is one of the daytime combat intermediary phases, taking place immediately before the First shelling starts. In this phase, allied and enemy fleets launch attacks with the intent to disable or remove enemy targets before the combat proper starts. This grants either fleet substantial advantages by possibly disabling key ships on the opposing side.
Battle Opening has the following structure:
- Opening ASW Shelling (OASW)
- Opening Torpedo Salvo
In case neither fleets meet the requirements, the sub-phase will be skipped.
Opening ASW Shelling (OASW)
Commonly referred to as OASW (opening ASW). All eligible ships will perform a regular ASW Shelling attack, following range order in the same fashion as the First Shelling Phase. As these opening attacks happen before the Opening Torpedo Salvo, they may disable or even sink enemy submarines before they have a chance to attack.
OASW has the following trigger conditions:
- The ship must be able to perform ASW shelling.
- Meet their specific ASW stat threshold and requirements:
| OASW Ship | ASW Stat Required[1] | Equipment Required[2][3] |
|---|---|---|
| Any Destroyer/Light Cruiser/Torpedo Cruiser/Fleet Oiler/Training Cruiser | 100+ ASW |  1 Sonar Equipped
|
| Any Coastal Defense Ship | 60+ ASW | 1 Sonar Equipped
|
| 75+ ASW | Total of 4+ ASW from equipment | |
   Kai Ni D    
|
Can OASW innately | N/A |
| Any Light Aircraft Carrier | 50+ ASW | +    Sonar + Any with 7+ ASW |
| Any Escort Carriers (CVE) | 65+ ASW | Any with 7+ ASW |
| 100+ ASW | +  Sonar + Any with 1+ ASW | |
    Kai Ni Go
|
N/A | Any with 1+ ASW |
|
N/A | 2 Autogyros   -or- 1 Helicopter 
|
    Kai Ni Juu
|
100+ ASW | +  Bomber Sonar + Seaplane Bomber or Rotorcraft |
- ↑ The Required ASW Stat does include visible equipment bonuses, but does not include improvement bonuses.
- ↑ Visible equipment bonuses or improvement bonuses do not count as equipment ASW (e.g. a +6 ASW equipment with +1 ASW bonus does not count as a +7 equipment but just as a +6 one).
- ↑ Regardless of their ASW stat,
Fighters or 
Recon Aircrafts cannot trigger any OASW.
- ↑ Only if Yamato has been ASW moded at some point.
See the list of Anti-submarine Weaponry and ASW Aircraft to better see what can help achieve OASW on a given ship.
Abyssals
Abyssal ships do not follow these rules. The following may perform OASW unconditionally:
- Destroyer Ha-Class Late Model Elite
- Destroyer Ni-Class Late Model Elite
- Light Cruiser Tsu-Class Flagship
- Light Carrier Nu-Class (Elite III, Elite IV, all Kai Elite, all Kai Flagship)
- Ancient Destroyer Princess (all variants)
- Abyssal Kuriles Princess (all variants)
- Destroyer Forest Princess (Damaged variants unconfirmed)
Other abyssals cannot perform OASW.
Opening Torpedo Salvo
Commonly referred to as oTorp (opening torpedo). Eligible ships will fire an Opening Torpedo attack. This attack behaves similarly to the Closing Torpedo attack, with the difference that it will be launched regardless of the ship's damage state.
Opening Torpedo salvo has the following trigger conditions:
- The ship is a Submarine (SS/SSV), at Lv.10 or higher.
- While other Abyssal ships are Lv.1, all Abyssal Submarines are Lv.50,
- Abyssal submarines have an additional requirement of being Elite or Flagship tier.
- The ship is equipped with a
Minisub Midget Submarine.
- Midget Submarines are the Type A Kouhyouteki
, Type C Kouhyouteki
, and Type D Kouhyouteki Kai (Kouryuu Kai)
. - The Abyssal Cuttlefish Torpedo count as such for Abyssals, with other Abyssal equipment such as High-speed Abyssal Torpedo mod.2, despite being classified as Midget Submarine, do not enable oTorp.
- Midget Submarines are the Type A Kouhyouteki
This phase follows the same rules as Closing Torpedo Salvo, with some exceptions:
- Ships at Moderate or Heavy damage can still fire torpedoes.
- If only submarines are left in the opposing fleet, torpedoes will randomly target them, never dealing damage, and always being displayed as "miss".
After the Opening Torpedo Salvo, the Day Battle Shelling starts (if there are any remaining ships on either side left).