While there have been a couple female leaders in Sentai in recent years, Yuri is perhaps the last true full-time leader. Ran/Gekiyellow was chosen as the captain of the Gekirangers but rarely did anything that remotely resembled a leader. Kaoru (female Shinkenred) took over leadership responsibilities from Takeru and actually did lead the Shinkengers, but she was present for only 6 episodes. Yuri, however, was leader from day one with her team. It can be argued that the team moved with Tatsuya or that her and Tatsuya were co-leaders, but for the sake of arguement, I consider Yuri the leader of the Timerangers because she led them in battle and recruited Tatsuya.
Yuri is everything you would want a leader to be. She's tough, serious, strict, and has good leadership skills. In fact, she's one of the more serious pink rangers ever along with Sakura/Bouken Pink, though she doesn't have the smiling issues that Sakura has and can lighten up. She started out as a by the book leader, but eventually loosen up a bit by warming up to Tatsuya and eventually seemed like she didn't care that Domon and Honami were dating (at first she saw Honami as a threat to their mission). Eventually Tatsuya falls for Yuri but they were unable to be together because of the large time difference.
The reason why Yuri was serious and strict with her team was because she felt like she had a mission to accomplish. In the year 3000 she was a cop in the same anti-mafia division that her father was in. Her father and her family were murdered by a Londarz family criminal, who at the time was ordered by Don Dorunero. After Don Dorunero escaped to the year 2000, Yuri volunteered to go after him. Yuri felt that bringing Dorunero back to justice was her chance at redemption for her family. When she was unable to bring him back alive, Yuri felt that she had failed her mission.
Yuri is one of the more well developed pink sentai warriors ever. Given her families past, her sense of a mission to accomplish, and how she eventually warms up to Tatsuya and her team, especially since she's the only girl on her team.