I usually don’t bother writing out strategy guides for the games covered on this website for the simple reason that they’re usually covered in various official and unofficial sources. However, One Night Kiss is pretty much undocumented, save for some notes left by a Japanese fan; Since I had to research the game extensively, I decided to write down my findings since some of the game’s systems and collectibles can be quite obtuse.
In each chapter of the game you will alternate between playing as Saya, armed with a sword, and Aoyama, armed with a golden shotgun. The main objective is to talk with specific NPCs, labeled on the map with a red cross, in order to ascertain the location of that chapter’s boss fight. As the game goes on, the investigative part is largely done away with and replaced with mob fights littered through the map which you have to complete before gaining access to the boss. As Saya, boss fights involve finding the correct openings to hit the enemy enough times to build up her blood meter, after which she will enter her awakened state and be able to destroy one of the enemy’s limbs. Once all of them are dealt with, she will need to trigger an execution minigame which is different for each enemy. Aoyama’s combat is much simpler; he can just damage the Chiroptera directly by shooting them when vulnerable.
Side-quests and collectibles
Most chapters in the game feature some sort of side-objective given to you by an NPC, which generally involves retrieving a lost item in a specific area of the map or delivering a specific item to a different NPC. The quest givers are labeled on the map with a red exclamation mark, while you’re left to your own devices on where to find the items or related NPCs. There’s also one NPC per character, generally located somewhere near the starting area, which will inform you of available side-quests, a middle-aged man called Uniform Angel for Saya and a high-school girl called Fashionable Thief for Aoyama.
The reward for these side activities is alternate costumes for both Saya and Aoyama, which can be equipped in their respective headquarters.
This game’s collectibles take the form of e-mails. Each character has their own series, with Saya’s being a tourist guide to Shiki New Town and Aoyama’s being an episodic story released through a mailing list. Each e-mail spawns in different chapters and can be obtained by walking in a specific area of the map. The reward for collecting all of the e-mails is, again, an alternate costume for Saya and one for Aoyama.
It should be noted that, possibly due to a bug, Saya’s e-mails can only be collected when playing on Adventure (easy) Mode. The NPC meant to start the quest simply won’t appear on Action or Perfect Kiss mode.
Modes and Difficulties
When first starting the game, only One Night Kiss mode is available. This is your standard campaign. Two difficulties are available from the start, “Adventure Mode” in which combat is easier and you’ll automatically block enemy attacks, and “Action Mode”, where the player takes more damage, the enemies have more health and the number of required mob fights is increased.
Completing the game once on either difficulty will unlock Perfect Kiss mode, which is an extra-hard mode reminiscent of Killer8 in which the player is given new tools to deal with the upped challenge, namely new weapons for both Saya (the sword she gets in the second season of the Anime show) and Aoyama (a grenade launcher). Not only is the challenge increased, but the number of obligatory mob fights is pushed to the point of absurdity. The Chiroptera in Perfect Kiss mode also sport alternate colors.
While most of the story is unaltered from the regular campaign, Perfect Kiss features some altered cutscenes in Chapter 21 and an alternate ending to the story. Completing this mode unlocks Blue Mountain mode.
Blue Mountain (a pun on the name Ao-yama) mode is a boss rush in which Aoyama is tasked with defeating all the game’s bosses in one go, even those that were originally faced by Saya, set to their Perfect Kiss difficulty. He will be equipped with his standard shotgun and his level is reset, meaning he won’t have access to any unlockable skill. Beating this gauntlet unlocks the final uniform for Saya, the one she used during the France arc of the show.
The game includes a level up system; when fighting enemy mobs in the sewers you will be occasionally rewarded with a health boost, an attack boost, new combo strings, more defense options and possibly other rewards I have not personally seen. Depending on the actions taken during battle (attacking, blocking, doing jumping attacks and so on) you will gain different kinds of experience; however, I have not been able to list every single upgrade, as during my third playthrough I was still getting “blocking experience” with Aoyama.
Once a playthrough is finished, all your experience, much like your unlocked costumes, gets carried over to the next one, regardless of the save file used.