It feels a bit strange talking about this profile. For years, Koume was a coveted card whose namesake came from IM@S Cinderella Girls. It was a part of the big Triad Primus deck and aided in their success and dominance during that time.
Koume came out in April 2016 with the release of Idolm@ster Cinderella Girls 2nd Season booster. Traditionally, prior to Koume, grabbing climaxes to hand was a fair gamble, relying on you to mostly top deck to hard draw climaxes. Given how the game was back during that time, there were very limited ways to mill your deck with the predominant profile for milling being Akatsuki if your set had that luxury. Koume was an interesting card that immediately became a powerful addition to any deck it was featured in.
Koume’s effect allows you to reveal up to the top four cards of your deck and add a climax from among them to hand. If you do, then you must discard a card. Koume was powerful as one of the sole means of forcing a climax to hand and was quite efficient at doing so. At worst, she was a free mill because there was no discard cost to her, unlike Akatsuki. Thanks to her, decks running her, especially that of Triad Primus, found great success in consistency at getting out their combos and making sure they were in better deck states through massive milling.
Subsequently, Koume was put into a large limitation list that heavily hampered Triad Primus specifically while also preventing other decks from popping up from using her ability as freely as before.
FGO/S87-073C 聖槍の真実 ベディヴィエール (center)
KGL/S95-P04PR 聖夜の贈り物 千花 (right)
Modern versions of Koume all have their effects proc usually when they’re sent to waiting room with exceptions for level 2 or above cards such as Bedivere here. Even with modern iterations, Koume is quite rare compared to other profiles. Furthermore, trends seem to dictate this to be an effect that’s more common for the colour yellow. Koume profiles at lower levels also have an additional restriction that only allows you to salvage a certain type of climax, whether that be a certain colour or type, forcing decks who wish to run the powerful profile to be built in a restrictive manner, unless the timing for the ability be swapped to something like on-reverse.
The main point is that Koume has never been reprinted in its original form at level 0 anymore, allowing the turn player to grab a climax perfectly for that exact turn. Almost, if not all modern Koume profiles are meant to give the player the climax advantage during their next turn. given the vast majority are based upon on-reverse or sent to waiting room. This may not seem too impactful, but remember that climax combos are one of, if not, the most powerful effects in the game, combining two cards with synergy to give you vast advantages. Koume’s effect on-play is enormous because, instead of waiting for the next turn, you can immediately get the snowball rolling and go from there. Koume is quite a powerful profile in the right hands. Use it wisely and you can clutch games or push for a large advantage gap between you and your opponent. Make sure to keep in mind the timings.