Gakusen Toshi Asterisk, Saijaku Muhai no Bahamut Recommendations
Besides Infinite Stratos, id say Gakusen Toshi Asterisk is the second most similar to this series. especially in terms of characters:
-Both MCs are the laid back type, Transfer student with a Hidden and mysterious past. They also are really powerful with hidden abilities.
-Both Main Heroines are the classic Stubborn Tsundere, princess who hates the MC at first for seeing them Naked or half Naked then challenges them to a fight.
Then after the fight starts to immediately gain feeling for them. They both are also kinda lacking in the chest area too. (This is all ep 1 so it isnt even spoilers).