Natsu-iro no Sunadokei

Two romantic comedies that deals with the main character traveling through time to alter future events.  

both have girls from the future 

The Endless Eight really reminded me of this OVA involving the theory of time travel/loops. There's also some emotion and drama in both series as well as comedy. (more in Haruhi). Both anime(s) are something to keep an eye on. 

It seems like both of these animes have time travel in them and also, someone they love dies/gets hurt and both MC want to bring them back to how they were before. 

Both heavily use time travel as part of the actual plot to save someone. There is also romantic elements involved in both of these anime. However, Boku dake ga Inai Machi does a much better job 

Both have the same feeling and are eroge adaptations. Both are 2 ep. OVA. 

Both are ovas that are about romance and timetravel. 

Both series are short and have a love triangle as a main theme. The male character is also dating a girl who isn't allowed to stay late at night because of her strict parent. Ending is a little bit different though. 

A very similar love triangle, with charas that have a similar personality. The main girl suffers a serious accident in both, that has a deep impact in the main boy´s life.  

Natsuiro no sunadokei is also about time travel but its much better than Kakyuusei 2.  

The same plot where a boy is surrounded by many girls. The same type of love triangle. The main characters share the same personality: the boy is in love with a shy beautiful girl and asks for help to his friend which is a energetic girl that is in love with him. But, They differ a lot in the end, one has a happy end, other has a tragic end.