Heiji Hattori and Kazuha Toyama
Background
Heiji and Kazuha have been best friends since childhood and has kept close together throughout the years. Kazuha is perhaps the most important and Closest person to him out of everyone in the series, and Heiji being the most important person in her world as well. They go just about everywhere together from Vacations to Dinner dates and Mystery Cases, There are very rare episodes where the two aren't together because they always travel together to most of the places they go to. Kazuha and heiji both share Twin Good - Luck charms that has the chain that kept them bonded together from when they where children and have worn them throughout the years. Heiji has been shown to be very jealous when another man takes a intrest in her, as seen when he was clearly jealous when she told him she was hugging another man. In Their Love life status, Kazuha seems to be a few levels ahead of heiji, She has her feelings for him made out pretty clear (Love) while Heiji is still at a kindergarden level in the feelings department, but together they are about the same level as shinichi and ran. In The 7th movie Crossroad in the Ancient Capital Heiji realizes that Kazuha was his first love and remains to be his true love from that day. Though they may bicker and make fun of each other, Heiji and Kazuha both care for each other very deeply and cares for the others safty and would even risk their own Safty for the cost of the others.