Marco Ikusaba

Marco Ikusaba is the Seventh diary owner, sharing his position with the love of his life Ai Mikami. A skilled street brawler, Marco is devoted to Ai and they work as a perfect battle couple, using the "Exchange Diary" to help one another in the survival game.

Personality
Marco can come across as a typical street brawler, appearing quite cocky, energetic and always ready for a fight. He is quite proud of techniques, particularly his cross chop move. Because of numerous fights he got into as a teenager, Marco is a skilled fighter, being quick on his feet and good with his fists.

Marco is devoted to Ai, having made a vow to protect her during their high school years together. Workign together, they consider their love to be perfect and unbreakable. Marco becomes particularly outraged by the actions and cowardice of Yukiteru Amano and he fails to protect his girlfriend Yuno Gasai from his and Ai's attacks, Marco willingly putting his life on the line to protect Ai. He tries to man up Yuki so he can protect Yuno, acting as a foil to Yuki and Yuno. Marco is very concerned over his appearance in his adult years, having long hair which he stylises into a curled cone shape resembling a perm or a pompadour hairstyle, and often carries a comb around with him.

Marco and Ai share the "Exchange Diary", which doubles as two mobile phones. The diaries record everything Marco and Ai, focusing on each other in a similar light to how Yuno's "Yukiteru Diary" works. If one of the diaries is destroyed, the owner will disappear and not both. Marco is given an Apprentice Diary to use to hide the fact he and Ai are Seventh, having "The Unbeatable Brawl Diary", which predicts the moves that his opponents will make and how he will defeat them.

Backstory
Fourteen years ago, the orphaned Marco had been taken in at some point by Kamado Ueshita, who would become the Eighth diary owner. Whilst visiting the Sakurami observation tower, Marco met the young Ai who had been abandoned by her parents that day. Marco told Ai if she believed that day to be the worst day of her life, than the next day would be better. Marco then invited Ai to live with him and Kamado.

The anime extended their history together, showing Marco and Ai in high school. On Ai's first day in high school, she followed Marco around, who was her senior. Marco at first objected to being followed around by a first year, but he lets her, and they grow close, implying they started dating. Marco and Ai visit the Sakurami Tower, where a chapel has been built, Ai suggesting it as the perfect place to get married, and she began a diary based around Marco.

Ai found a letter apparently from Marco, inviting her to a warehouse. Three fellow students appeared, having fooled Ai into coming, and sexually assault her. Marco, realising something was not right after Ai fails to answer her phone, and races to the warehouse where he is horrified by what he sees. In a blind rage, Marco attacks Ai's assailants. One draws a knife, but Marco angrily kills the student with it. Later, Marco and Ai have gone to the tower, Marco horrified at his own actions and failure to protect Ai, and contemplates taking his own life with the knife. Ai stops him, promising to support him with his faults and fears, Marco equally vowing to protect Ai. The two then share their first kiss.

Battle of Love
Marco debuts in the story alongside the other diary owners at the survival game's first meeting held by Deus Ex Machina. Marco targets Yuki like the other owners for killing the Third diary owner, Takao Hiyama, considering him a "tough opponent". Presumably Ai was not present to hide the fact she and Marco shared the same position as the Seventh diary owner.

Marco appears much later with Ai. After Kamado gave Ouji Kosaka an Apprentice Diary to aid him in the liberation of Yuki, kidnapped by Yuno, her assistant Orin Miyashiro sends Marco, Ai, and fellow orphan Ta-kun to intercept Yuki and Yuno. However, Yuki abandonds Yuno and departs with his friends in Masumi Nishijima's car. Marco, Ai and Ta-kun pass Yuki and his friends on the highway, too late to intercept them.

Marco, Ai and Ta-kun are again sent to prevent Yuki's attempt to disable the powers of Kamado's server diary by turning off a nearby communications tower controlling the local phone signals. Yuki's plan falls apart when Yuno reappears to fight Marco and Ai. The couple break into Kosaka's house, Nishijima attempting to put up a fight against Marco but is easily defeated thanks to Marco's experience in fights. Marco and Ai, using their Apprentice Diaries, pursue Yuki, Yuno, Hinata Hino and Mao Nonosaka through Kosaka's house, Ai injuring the latter two with her knives. Marco and Ai confront Yuki and Yuno in a secluded room through a trap door, unaware of the crumbling relationship between Yuki and Yuno.

Aru Akise and Kosaka manage to disable the communications tower, leaving Marco and Ai apparently powerless. However, the two then reveal their Exchange Diaries, proclaiming them to be "diaries of love". Marco tells Yuki that the fight they are about to have is a battle of love between couples. Yuno persuades Yuki to release her from the ropes around her wrists, and fights Marco and Ai single-handidly, blocking Ai's throwing knives with amazing skills, inspired to fight after Yuki praises her. Stunned by this, Marco and Ai issue their "trump card" and escape through the trap door.

Taking Hinata and Mao outside, Marco and Ai heal them just as Ta-kun sets Kosaka's house on fire. The pair head back inside to finish off Yuki and Yuno. As the house burns down around them, Yuno and Ai get into a cat fight. Ai trips over a carpet, giving Yuno an opening, only for Marco to jump in and protect Ai, getting Yuno's knife stabbed into his arm. Ai manages to disable Yuno. Yuki runs in and Marco angrily berates him for not protecting Yuno. Yuki admits he is useless but cannot change his ways, Marco angrily throwing off the side of a balcony. He steals Yuki and Yuno's phones and escapes with Ai.

The Sakurami Tower
Marco and Ai reappear, Marco giving Yuno a phone call whilst she is hospitalised, requesting that she, Yuki and his father Kurou Amano come to the Sakurami Tower if they want their diaries back. Yuki, Yuno and Kurou arrive at the tower where they find Marco and Ai waiting for them, dressed as though ready to get married. It is revealed Ai had discovered Marco's plan to buy her an enagement ring and propose to her, leading to her original plan to marry in the tower's chapel.

Marco quickly beats down Kurou, holding him hostage and challenging Yuki to defeat him in order to save his father, and his diary. Yuki charges at Marco, but is easily defeated. Yuno makes a move, attacking Ai and reveals the diaries on display are fakes, and Ai is hiding their real diaries in her bouquet. Part of the tower suddenly explodes, Ta-kun contacting Marco and Ai through the tower's soundspeakers and telling them he is destroying the tower as per a time limit he put on their operation, leaving his former comrades to their own ends. Marco and Ai race to the elevator, taking Kurou with them.

In the elevator, the two recall their promise to marry one another, Marco vowing to prove that their love is real compared to that of Yuki and Yuno. Upon entering the top floor where they first met, Marco and Ai are surprised to find Yuno alone waiting for them. Yuki speaks through the soundspeakers, claiming he is too afraid to fight and will be helping Yuno from afar. Enraged, Marco fights his way past Yuno and races to the control room to confront Yuki whilst Ai holds down Yuno. Marco enters the control room, finding that Yuki is not there. Running back to the observation floor, Marco realises it was a trap. Yuki appears, trying to take out Ai's diary with a dart but misses by inches. Yuno frees herself from Ai's grasp and slashes her throat with a knife. Distraught, Marco races to save Ai just as the roof caves in, ignoring Kurou as he escapes the tower with one of Marco and Ai's parachutes. Yuki, Yuno and the dying Ai survive but become trapped under rubble. Marco, unwilling to leave Ai behind, uses a metal pole to dig out his beloved, inspiring Yuki to help him after chastising him for being a coward. Marco manages to lift the rubble covering Yuki, Yuno and Ai partway, revealing a piece of shrapnel has impaled him through the adbomen, Marco apologising to Ai that he got carried away.

Yuki convinces Yuno to help him lift the rubble, and they help Ai out of the rubble only to find she has already died from blood loss. Cradling Ai in his arms, Marco tosses his last parachute to Yuki so he and Yuno can escape the tower. Marco instructs Yuki not to look down at him with sympathetic eyes, and shoos Yuki and Yuno away, who depart the tower in the parachute.

Marco sees his diary gains a Dead End, concluding his and Ai's dream of becoming gods and eternal lovers was not going to happen, but wonders if this moment between them is eternal. The tower collapses, killing Marco and Ai, and eliminating them from the game.

The Third World
In the third parallel world created when Yuno, Muru Muru, Yuki and Minene Uryu perform a time leap two years back in time, Marco and Ai are seen at Kamado's orphanage. They witness the explosions and events occuring at Sakurami Elementary School between Muru Muru and Minene, Kamado receiving an unexpected phone call from the mayor John Balks regarding the future of her orphanage, asking for her help in the future.

Two years later, Marco and Ai are shown to have married and Ai is now pregnant, happy together among the many residents of Sakurami City.

Future Diary: Paradox
In Future Diary: Paradox, Aru Akise and Muru Muru are standing in for Yuki and Yuno after Muru Muru accidentally killed Yuno and Yuki is wounded by Hiyama. After Akise altered the events at the Omekata temple, Muru Muru vowed to rewind time after Yuki is healed to ensure the game runs properly. Akise races to stop her, aided by Marco, Ai, Orin, Reisuke Houjou and Tsubaki Kasugano. Marco personally fights Muru Muru whilst Tsubaki leads Akise to the entrance to Muru Muru's record hall, although Muru Muru ends up succeeding and reverses time.

Trivia

 * Marco is named after Mars, the Roman god of war.