Heartache 101 Sour Into Sweet

Heartache 101: ~Sour Into Sweet~ is a freeware customizable Dating Sim created by flowerthief, previously known for Idolcraft.

One day at school, Ferdinand agreed to a bet proposed by his childhood friend Miki, following a conversation regarding their respective skill (or lack thereof) at finding someone to date. Under the conditions of the bet, the two of them would be given 101 days to find and hold onto a significant other. If either of them were to succeed at these criteria while the other failed, they would be considered the victor.

Working toward the goal in order to prove himself to his friend, Ferdinand meets many girls.
 * Miki Nakajima, Ferdinand's tomboyish childhoood friend
 * Keika Ikeda, Miki's rich and eccentric friend
 * Tsubasa Onishi, a girl who solves already-closed detective cases given to her by her father to keep her mind sharp
 * Shihoko Kaneshiro, the School Idol and star of the tennis team
 * Riho Kaneshiro, Shihoko's overshadowed younger sister
 * Akari Sato, a shy acquaintance of Keika's who suffers from neurotic disorders
 * Hinami Hiraoka, Akari's overly energetic friend who frequently misses school to travel overseas with her family
 * Chiemi Akizawa, the hard to find Secret Character
 * and many, many more possibilities...

The game can be acquired for free at RPGMaker.net

"Akari:
 * Absurdly High Level Cap: Stats go up to 100. While raising these stats to max value will continue to increase the affection bonus from talking to girls, it is still possible to max out affection levels within the time limit without doing so. The other uses of the stats are storyline attribute checks (which never require values higher than 50 in the core game) and giving advice to girls (which will have a 100% success rate somewhere between 50 and 60).
 * Always Second Best: While she never displays anything other than love for her sister, Riho feels that Shihoko is better than her at everything.
 * Amateur Sleuth: Tsubasa, who works out the solutions to already-solved cases given to her by her father as a form of training.
 * Boyfriend Bluff:
 * Breaking the Fourth Wall: The Chocolate Lady, who's apparently somewhat aware of how unrealistically small the in-game world is, and expresses her displeasure of the random generator that forces her to walk around town and share her always sufficient supply of chocolates with strangers every day.
 * Brilliant but Lazy: Tsubasa at studying.
 * Brown Note: Requiem of Surrogation.
 * Chaste Teens: Seemingly averted, as Miki and Keika talk about having boyfriends, and express interest in dating some of the (unseen) male characters.
 * Childhood Friend Romance: Ferdinand and Miki
 * Covert Pervert: Akari gets more and more funny ideas the more she likes Ferdinand. Cute? Sure, but it get's disturbing when you realize she's also one of the three girls in the game who are underage. Goes way over the top after she falls in love with him:

Ferdinand:

Akari:

Ferdinand:

Akari:

Ferdinand:

Akari:

Ferdinand:

Akari:

...

Ferdinand:

Akari:

Ferdinand:

Akari:

Ferdinand:

Akari:

Ferdinand:

Akari:

Ferdinand:

Akari:"


 * Derailing Love Interests: Somehow they have to make it moral for Ferdinand to take Keika from her boyfriend.
 * Drugs Are Bad: There's a drug dealer who will offer to give you a special pill that boosts all of your stats considerably. The downside? The withdrawal is absolutely painful -- a few days later, your stats start randomly dropping, sometimes to the point where you're actually worse off than you were before taking the pill.
 * Devoted to You: Chiemi to Ferdinand.
 * Easy Level Trick: There are lots of bonus items and features scattered throughout the game that give Ferdinand an extra edge in boosting his stats or his chances with dates. Probably the most famous of these are the chocolates, which are handed out by the ridiculously meta Chocolate Lady.
 * Fragile Flower: Chiemi.
 * Game Mod: One of the features of the game is that it is relatively easy for people to create images, profiles, music, and stories for their own characters and add them to the cast.
 * The Glorious War of Sisterly Rivalry: Shihoko and Riho are almost a textbook example.
 * Genki Girl: Hinami. Miki and Shihoko can be rather energetic at times, as well.
 * Guide Dang It: Certain scenes in each girl's path require one of Ferdinand's attributes to be raised to a certain level. While the required attributes for each character are relatively easy to figure out, there is no advance warning for when these scenes come up, and if the requirements aren't met, then the rest of that girl's path can be closed of for the remained of the game.
 * He Who Must Not Be Seen: Literally every male character in the game. Only the girls have character portraits.
 * Joke Item: The top. Purchasable from the convenience store for only 200 yen, this item can only be given to Tsubasa or Hinami (technically, it can be given to anybody, but everybody else considers it to be a bad gift, and thus there is no benefit to doing so)
 * Love Redeems:
 * Maybe Magic, Maybe Mundane: It's never made clear whether  that appears to Akari each night is real or simply a hallucination.
 * Medium Awareness: The Chocolate Lady knows that she's an NPC in a Dating Sim, and thus gives hilariously fourth-wall-breaking advice and commentary which leaves poor, Genre Blind Ferdinand confused.
 * Nice Job Fixing It, Villain: Ferdinand needs a girlfriend to win his bet against Miki. Keika (Miki's friend) agrees to arrange a meeting between him and Akari to help him out . Her intent was that Akari would prove to be so antisocial and unapproachable that any time Ferdinand spent with her may as well have been wasted... up until Ferdinand actually manages to get close to Akari.
 * Not What It Looks Like: While racing against Miki, Ferdinand trips and falls, landing on top of her. Miki's classmate, Riho, was watching at the time and concludes that Ferdinand meant to end up on top of Miki.
 * Oblivious to Love: Ferdinand to Miki's.
 * Ordinary High School Student: Ferdinand
 * Panty Shot: Unseen by the player, but one scene with Tsubasa has her tripping, accidentally exposing her underwear to Ferdinand.
 * Returning to the Scene:
 * Rich in Dollars, Poor In Sense: Keika comes from a wealthy family. She also has a personality occasionally bordering on Cloudcuckoolander.
 * School Idol: Shihoko
 * She Is Not My Girlfriend: Ferdinand and Miki
 * Shout-Out: Of course I knows the hacker.
 * Shrinking Violet: Akari
 * Sibling Triangle: Can happen with Riho and Shihoko.
 * Stalker with a Crush: Chiemi.
 * Teacher-Student Romance: Shihoko..
 * There Are No Therapists: Played with. Akari is being treated by the school counselor, but it soon becomes clear that he's out of his depth since he's an academic counselor, not a psychological one. She's also receiving treatment from the local hospital..
 * Tsundere: Miki, Riho.
 * Unexpected Gameplay Change: Most of the game is a Visual Novel/Dating Sim. The school day itself is a kind of Board Game-like challenge, with dice-rolling and items that move you a certain number of squares. Ferdinand's part-time job as a janitor requires the player to beat a level of either Pac-Man or a Stealth Based Mission.
 * Vitriolic Best Buds: Ferdinand and Miki.